Following that patch referenced below, the top SUPGRPS
field would produce a segmentation fault and ps SUPGRP
would often show "(null)". Such problems resulted from
some faulty logic in the status2proc() routine dealing
with 'Groups' (supgid) which served as a source field.
For many processes the original code produced an empty
string which prevented conversion to the expected "-".
Moreover, prior to release 3.3.15 such an empty string
will become 0 after strtol() which pwcache_get_group()
translates to 'root' yielding very misleading results.
So, now we'll check for empty '/proc/#/status/Groups:'
fields & consistently provide a "-" value for callers.
[ we'll also protect against future problems in that ]
[ new qualys logic by always ensuring valid 'supgrp' ]
[ pointers - logic which revealed our original flaw! ]
Reference(s):
. original qualys patch
0071-proc-readproc.c-Harden-supgrps_from_supgids.patch
Signed-off-by: Jim Warner <james.warner@comcast.net>
Jim Warner [Fri, 25 May 2018 05:00:00 +0000 (00:00 -0500)]
top: sanitized some potentially corrupt 'Inspect' data
This guards against rcfile 'Inspect' entries which may
include non-printable characters. While this shouldn't
occur, we have no real control over those crazy users.
[ and, while such data can't be used maliciously, it ]
[ does adversely impact such a user's screen display ]
Signed-off-by: Jim Warner <james.warner@comcast.net>
Jim Warner [Thu, 24 May 2018 05:00:00 +0000 (00:00 -0500)]
top: prevent buffer overruns in 'inspection_utility()'
When a Qualys patch was reverted as being unwarranted,
1 specific problem their patch had, in fact, prevented
was re-introduced. This patch corrects that oversight.
Jim Warner [Wed, 23 May 2018 05:00:00 +0000 (00:00 -0500)]
top: add another field sanity check in 'config_file()'
Until the Qualys security audit I had never considered
it a possibility that some malicious person might edit
the top config file to achieve some nefarious results.
And while the Qualys approach tended to concentrate on
the symptoms from such an effort, subsequent revisions
more properly concentrated on startup and that rcfile.
This commit completes those efforts with 1 more field.
Signed-off-by: Jim Warner <james.warner@comcast.net>
Jim Warner [Sun, 20 May 2018 05:00:00 +0000 (00:00 -0500)]
top: don't mess with groff line length in man document
I've long since forgotten why the attempt to influence
groff line lengths was made. However, I did receive an
email regarding problems formatting postscript output.
Hopefully this patch will eliminate any such problems.
Signed-off-by: Jim Warner <james.warner@comcast.net>
Craig Small [Sat, 19 May 2018 12:10:11 +0000 (22:10 +1000)]
ps: Increase command selection field to 64
The library now presents command names up to 64 characters, in line with
the kernel changes. ps command name selection (the -C option) now also
is 64 characters long.
Jim Warner [Sat, 19 May 2018 05:00:00 +0000 (00:00 -0500)]
top: just respond to the increased command name length
The command name for running tasks is displayed by top
in a variable length field, so the increase from 16 to
64 bytes was not a problem. However, there's one place
where top is sensitive to length - insp_view_choice().
So, this patch just bumps a buffer used to display it.
Jim Warner [Fri, 18 May 2018 05:00:00 +0000 (00:00 -0500)]
top: Prevent out-of-bounds writes in PUFF(). __Tweaked
This commit moves some overhead to the Batch mode path
where it's needed. And given the new 'else if' test we
can delete some now redundant logic in the other path.
This patch addresses a potential (but unlikely) buffer
overflow by reducing, if necessary, a memcpy length by
3 bytes to provide for an eol '\0' and 2 unused buffer
positions which also might receive the '\0' character.
[ note to future analysis tool: just because you see ]
[ binary data being manipulated in the routine, that ]
[ doesn't mean such function was passed binary data! ]
Jim Warner [Fri, 18 May 2018 05:00:00 +0000 (00:00 -0500)]
top: Fix out-of-bounds read/write in show_... REVERTED
I'm reverting this patch to prepare for some alternate
solution. In that solution I will address point #1 but
point #2 is based on a wrong assumption. There will be
no binary data ever found in the 'glob' passed to this
show_special() function. It is now always simple text.
------------------------------------------------ original commit message
This patch fixes two problems:
1/ In the switch case 0, if sub_end is at the very end of lin[], the two
null-byte writes are off-by-two (a stack-based buffer overflow). Replace
this end-of-string "emulation" with an equivalent test on ch (and then
goto/break out of the loop).
2/ "sub_end += 2" jumps over the null-byte terminator in lin[] if the
line contains a raw (without a tilde) \001-\010 character. Detect such a
null-byte terminator and goto/break out of the loop.
Note: in the case of a raw \001-\010 character, the character at
"sub_end + 1" is never processed (it is skipped/jumped over); this is
not a security problem anymore (since 2/ was fixed), so we decided not
to change this behavior, for backward-compatibility.
------------------------------------------------------------------------
Jim Warner [Fri, 18 May 2018 05:00:00 +0000 (00:00 -0500)]
top: prevent buffer overflow potential in all routines
Whereas that original patch (since reversed) addressed
some symptoms related to manually edited config files,
this solution deals with root causes. And it goes much
beyond any single top field by protecting all of top's
fields. Henceforth, a duplicated field is not allowed.
Jim Warner [Fri, 18 May 2018 05:00:00 +0000 (00:00 -0500)]
top: Prevent buffer overflow in calibrate_... REVERTED
Here, again, we have an example of attacking a problem
by addressing the symptoms. And that assertion made in
the original commit message is true if only if someone
had manually (maliciously) edited the top config file.
So let's reverse the original patch & thus prepare for
a proper solution addressing the cause, not a symptom.
Jim Warner [Fri, 18 May 2018 05:00:00 +0000 (00:00 -0500)]
top: Prevent integer overflows in procs_re... REVERTED
That patch referenced below is being reverted because:
. By design, no other top macro looks like a function.
Instead, they all contain some minimal capitalization.
The 'grow_by_size' macro stands out like a sore thumb.
. We would need to approach 400+ million tasks for for
the 1st addressed problem to produce integer overflow.
. And a 2nd check against SSIZE_MAX remains a mystery.
Me thinks a system on which top is running will suffer
ENOMEM before we need to worry about integer overflow.
Rather than validate the window's 'sortindx' each time
it was referenced (as was done in the patch below), we
now ensure the validity just once when the config file
is read. Thereafter, a running top will police bounds.
Here's yet another example of dealing with a potential
problem at the symptom level, instead of addressing it
at the source. So, we will reverse that original patch
referenced below in preparation for a proper solution.
[ at the least, this ugly code should have used that ]
[ existing MAXTBL macro, making it a little prettier ]
Jim Warner [Fri, 18 May 2018 05:00:00 +0000 (00:00 -0500)]
top: other graph_cpus, graph_mems, and summ_mscale fix
This patch replaces an original patch referenced below
which has now been reversed. We now validate variables
'graph_cpus', 'graph_mems' and 'summ_mscale' just once
at startup. Thereafter, top enforces the proper range.
[ we afford the same treatment to that 'task_mscale' ]
[ variable, which was ignored in the original patch. ]
Jim Warner [Fri, 18 May 2018 05:00:00 +0000 (00:00 -0500)]
top: Check graph_cpus, graph_mems, and sum... REVERTED
The variables graph_cpus, graph_mems & summ_mscale are
all well managed in a running top. They were, however,
each vulnerable to tampering via the rcfile. So rather
than continually addressing the symptoms, we'll attack
the root cause just once at startup in the next patch.
Jim Warner [Fri, 18 May 2018 05:00:00 +0000 (00:00 -0500)]
top: Do not default to the cwd in configs_r... Tweaked
While it's only documented (so far) in commit text and
an occasional email I've tried to maintain some coding
standards primarily for reference/navigation purposes.
They also served, I felt, as useful mental challenges.
Someday I will get around to formerly documenting them
but in the meantime here are the ones for this commit:
. functions are grouped into logical (i hope) sections
. functions & sections are ordered to avoid prototypes
. function names are alphabetical within every section
. all functions & sections must be referenced in top.h
This patch just attempts to honor the above standards,
while also covering this new behavior in the man page.
[ please note that the net result of these 2 patches ]
[ is simply to avoid pathname truncations should our ]
[ limit of 1024 be exceeded. they do not have a role ]
[ in solving the 'local privilege escalation' issue. ]
[ and we can never prevent a user from setting their ]
[ HOME var to a directory writable by some attacker! ]
[ the only real protection for that CVE-2018-1122 is ]
[ those soon to be enhanced rcfile integrity checks, ]
[ achieved through several of the following patches. ]
Craig Small [Fri, 18 May 2018 22:14:06 +0000 (08:14 +1000)]
pgrep: Remove >15 warning
As comm length can be longer than 15 characters with newer kernels, it
doesn't make sense to have a warning when you make the match string
longer than this.
As a side-effect, it removes the false-positive you got when you used
long regex matches (see issue #92 )
Craig Small [Fri, 18 May 2018 22:04:19 +0000 (08:04 +1000)]
library: Increase comm length to 64
For many years, the comm length has been set to 16. Previously to that
it was 8. This means for things like kworkers they all have very cryptic
names. The kernel is now going to increase this size to 64, so the
procps library will follow this length increase.
System tools may also increase their default length to 64, or keep it at
16; there is only so much screen real estate.
1/ Because snprintf() returns "the number of characters (excluding the
terminating null byte) which would have been written to the final string
if enough space had been available", _eol may point past the end of _str
and write out-of-bounds (in Batch mode).
2/ _eol is never checked against _str, so "while (*(--_eol) == ' ');"
may point _eol below _str and write out-of-bounds (in Batch mode).
3/ Sanity-check Pseudo_row to protect the strcpy().
top: Fix out-of-bounds read/write in show_special().
This patch fixes two problems:
1/ In the switch case 0, if sub_end is at the very end of lin[], the two
null-byte writes are off-by-two (a stack-based buffer overflow). Replace
this end-of-string "emulation" with an equivalent test on ch (and then
goto/break out of the loop).
2/ "sub_end += 2" jumps over the null-byte terminator in lin[] if the
line contains a raw (without a tilde) \001-\010 character. Detect such a
null-byte terminator and goto/break out of the loop.
Note: in the case of a raw \001-\010 character, the character at
"sub_end + 1" is never processed (it is skipped/jumped over); this is
not a security problem anymore (since 2/ was fixed), so we decided not
to change this behavior, for backward-compatibility.
- Make sure i is at least 1 before "i - 1" and "--i".
- Initialize endpflg (to 0, as it was originally, since it is static)
before the "for" loop (the "break" may leave endpflg uninitialized,
for example).
top: Prevent buffer overflow in calibrate_fields().
pflgsall[] can contain PFLAGSSIZ = 100 elements, each iteration of the
loop can write 3 elements to pflgsall[], and there are EU_MAXPFLGS = 58
iterations: a buffer overflow (it can be triggered via the configuration
file, for example, by filling "fieldscur" with the "sortindx" flag).
The safety of the critical function task_show() depends on the sanity of
Screen_cols. Just copy the tests on w_cols to Screen_cols (from the same
function adj_geometry()).
Several of these buffer overflows can actually be triggered (through the
configuration file for example): in config_file(), inspection_utility(),
and show_special().
The default action for SIGURG is to ignore the signal, for example.
This is very similar to the patch "ps/display.c: Always exit from
signal_handler()."
Every time sortindx is used as an index, or loaded from the
configuration file. Otherwise it leads to out-of-bounds reads and
arbitrary code execution.
Otherwise they may lead to out-of-bounds writes (snprintf() returns the
number of characters which would have been written if enough space had
been available).
Also, make sure buf is null-terminated after COLPLUSCH has been written.
If the HOME environment variable is not set, or not absolute, use the
home directory returned by getpwuid(getuid()), if set and absolute
(instead of the cwd "."); otherwise, set p_home to NULL.
To keep the changes to a minimum, we rely on POSIX, which requires that
fopen() fails with ENOENT if the pathname (Rc_name) is an empty string.
This integrates well into the existing code, and makes write_rcfile()
work without a change.
Also, it makes the code in configs_read() easier to follow: only set and
use p_home if safe, and only set Rc_name if safe (in all the other cases
it is the empty string, and the fopen() calls fail). Plus, check for
snprintf() truncation (and if it happens, reset Rc_name to the empty
string).
Important note: top.1 should probably be updated, since it mentions the
fallback to the current working directory.
Check the return value of sscanf() to make sure that all input items are
properly initialized.
In extended mode (x_option), one_proc() loads the values of start and
perms during one iteration of the while loop, and displays them during
one of the following iterations, but start and perms are variables local
to the while loop: move them out of the while loop, to the beginning of
the function.
Also, display a mapping only if cp2 is properly initialized; otherwise
(for example), mappings that do not belong to a selected range are
displayed, and with a NULL mapping name:
If "cp = strrchr(mapbuf_b, '/')" then this function returns, and
otherwise there is no '/' in mapbuf_b and "cp = strchr(mapbuf_b, '/')"
is always false: remove this second block, since it is never entered.
Also, constify a few things in this function.
In the headers, the space was misplaced; for example, "pmap -XX $$"
outputs "VmFlagsMapping" (without a space). Use justify_print() instead
of printf().
There was also an extra space in the output, because vmflags[] (from the
"VmFlags:" line) always ends with a space. Overwriting this last space
with a null byte fixes this misalignment.
vmflags[] is a 27*(2+1)=81 char array, but there are 30 flags now (not
27), and even with 27 flags this was an off-by-one overflow (the kernel
always outputs a flag with "%c%c ", so the last +1 is for a space, not
for the terminating null byte). Protect vmflags[] with a maximum field
width, as in the surrounding sscanf() calls.
Otherwise "the contents of the array remain unchanged and a null pointer
is returned" or "the array contents are indeterminate and a null pointer
is returned".
proc/readproc.c: Work around a design flaw in readeither().
readeither() caches (in new_p) a pointer to the proc_t of a task-group
leader, but readeither()'s callers can do pretty much anything with the
proc_t structure passed to and/or returned by this function. For
example, they can 1/ free it or 2/ recycle it (by passing it to
readeither() as x).
1/ leads to a use-after-free, and 2/ leads to unexpected behavior when
taskreader()/simple_readtask() is called with new_p equal to x (this is
not a theoretical flaw: 2/ happens in readproctab3() when want_task()
returns false and p is a group leader).
As a workaround, we keep a copy of new_p's first member (tid) in static
storage, and the next times we enter readeither() we check this "canary"
against the tid in new_p: if they differ, we reset new_p to NULL, which
forces the allocation of a new proc_t (the new "leader", or reference).
This always detects 2/ (because free_acquired(x,1) memsets x and hence
new_p); always detects 1/ if freed via free_acquired() and/or freeproc()
(very likely, otherwise memory may be leaked); probably detects 1/ even
if freed directly via free() (because the canary is the first member of
proc_t, likely to be overwritten by free()); but can not detect 1/ if
free() does not write to new_p's chunk at all.
Moreover, accessing new_p->tid to check the canary in case 1/ is itself
a use-after-free, so a better long-term solution should be implemented
at some point (we wanted to avoid intrusive and backward-incompatible
changes in this library function, hence this imperfect workaround).
proc/readproc.c: Prevent integer overflows in readproctab*().
If an integer overflow is about to be reached, call xalloc_err_handler()
(since it would have been caught by calloc() or reallocarray()) and then
exit(): these integer overflows are far from reachable, with the current
PID_MAX_LIMIT (2^22), so if they are there is something very wrong going
on. Note: we check the n_*alloc variables against INT_MAX even when they
are size_t because they are later stored as int in a struct proc_data_t.
proc/readproc.c: Fix double-free()s in readtask().
If QUICK_THREADS is not defined (it is not by default, but most
distributions enable it) and task_dir_missing is true (only on very old
kernels), then readtask() forgets to reset some of the struct proc_t t's
members, which later results in double-free()s in free_acquired().
For now, we simply synchronized the list of members to be reset with the
list of members freed in free_acquired().
proc/readproc.c: Fix use-after-free in readproctab2().
The memset() in the PROC_LOOSE_TASKS loop leaves a struct proc_t
uninitialized (the one at data+n_used), which leads to a use-after-free.
ps calls readproctab2(), but only if !TF_loose_tasks, and this U-A-F is
triggered only if PROC_LOOSE_TASKS, so there seems to be no vulnerable
call in the procps package itself (other users of the libprocps may be
vulnerable, though).
Check the return value of snprintf(), otherwise dst may point
out-of-bounds when it reaches the end of the dst_buffer (the snprintf()
always returns 1 in that case, even if there is not enough space left),
and vMAX becomes negative and is passed to snprintf() as a size_t.
This detects an integer overflow of "strlen + 1", prevents an integer
overflow of "tot + adj + (2 * pSZ)", and avoids calling snprintf with a
string longer than INT_MAX. Truncate rather than fail, since the callers
do not expect a failure of this function.
2/ Limit sz to INT_MAX, because the return value is an int, not an
unsigned int (and because if INT_MAX is equal to SSIZE_MAX, man 2 read
says "If count is greater than SSIZE_MAX, the result is unspecified.")
3/ Always null-terminate dst (unless sz is 0), because a return value of
0 because of an open() error (for example) is indistinguishable from a
return value of 0 because of an empty file.
4/ Use an unsigned int for i (just like n), not an int.
proc/readproc.c: Fix bugs and overflows in file2strvec().
Note: this is by far the most important and complex patch of the whole
series, please review it carefully; thank you very much!
For this patch, we decided to keep the original function's design and
skeleton, to avoid regressions and behavior changes, while fixing the
various bugs and overflows. And like the "Harden file2str()" patch, this
patch does not fail when about to overflow, but truncates instead: there
is information available about this process, so return it to the caller;
also, we used INT_MAX as a limit, but a lower limit could be used.
The easy changes:
- Replace sprintf() with snprintf() (and check for truncation).
- Replace "if (n == 0 && rbuf == 0)" with "if (n <= 0 && tot <= 0)" and
do break instead of return: it simplifies the code (only one place to
handle errors), and also guarantees that in the while loop either n or
tot is > 0 (or both), even if n is reset to 0 when about to overflow.
- Remove the "if (n < 0)" block in the while loop: it is (and was) dead
code, since we enter the while loop only if n >= 0.
- Rewrite the missing-null-terminator detection: in the original
function, if the size of the file is a multiple of 2047, a null-
terminator is appended even if the file is already null-terminated.
- Replace "if (n <= 0 && !end_of_file)" with "if (n < 0 || tot <= 0)":
originally, it was equivalent to "if (n < 0)", but we added "tot <= 0"
to handle the first break of the while loop, and to guarantee that in
the rest of the function tot is > 0.
- Double-force ("belt and suspenders") the null-termination of rbuf:
this is (and was) essential to the correctness of the function.
- Replace the final "while" loop with a "for" loop that behaves just
like the preceding "for" loop: in the original function, this would
lead to unexpected results (for example, if rbuf is |\0|A|\0|, this
would return the array {"",NULL} but should return {"","A",NULL}; and
if rbuf is |A|\0|B| (should never happen because rbuf should be null-
terminated), this would make room for two pointers in ret, but would
write three pointers to ret).
The hard changes:
- Prevent the integer overflow of tot in the while loop, but unlike
file2str(), file2strvec() cannot let tot grow until it almost reaches
INT_MAX, because it needs more space for the pointers: this is why we
introduced ARG_LEN, which also guarantees that we can add "align" and
a few sizeof(char*)s to tot without overflowing.
- Prevent the integer overflow of "tot + c + align": when INT_MAX is
(almost) reached, we write the maximal safe amount of pointers to ret
(ARG_LEN guarantees that there is always space for *ret = rbuf and the
NULL terminator).
1/ Replace sprintf() with snprintf() (and check for truncation).
2/ Prevent an integer overflow of ub->siz. The "tot_read--" is needed to
avoid an off-by-one overflow in "ub->buf[tot_read] = '\0'". It is safe
to decrement tot_read here, because we know that tot_read is equal to
ub->siz (and ub->siz is very large).
We believe that truncation is a better option than failure (implementing
failure instead should be as easy as replacing the "tot_read--" with
"tot_read = 0").
1/ Do not read past the terminating null byte when hashing the name.
2/ S[x] is used as an index, but S is "char *S" (signed) and hence may
index the array out-of-bounds. Bit-mask S[x] with 127 (the array has 128
entries).
3/ Use a size_t for j, not an int (strlen() returns a size_t).
Notes:
- These are (mostly) theoretical problems, because the contents of
/proc/PID/status are (mostly) trusted.
- The "name" member of the status_table_struct has 8 bytes, and
"RssShmem" occupies exactly 8 bytes, which means that "name" is not
null-terminated. This is fine right now, because status2proc() uses
memcmp(), not strcmp(), but it is worth mentioning.
This function is unused (SIGNAL_STRING is defined by default, and if it
is not, procps does not compile -- for example, there is no "outbuf" in
help_pr_sig()) but fix it anyway. There are two bugs:
- it accepts non-hexadecimal characters (anything >= 0x30);
- "(c - (c>0x57) ? 0x57 : 0x30)" is always equal to 0x57.
proc/sysinfo.c: Ensure null-termination in getstat().
There was a "buff[BUFFSIZE-1] = 0;" but there may be garbage between
what is read() (less than BUFFSIZE-1 bytes) and this null byte. Reuse
the construct from the preceding getrunners().
ps/sortformat.c: Double-check chars in verify_short_sort().
To avoid an out-of-bounds access at checkoff[tmp]. The strspn() at the
beginning of the function protects against it already, but double-check
this in case of some future change.
Right now, "we _exit() anyway" is not always true: for example, the
default action for SIGURG is to ignore the signal, which means that
"kill(getpid(), signo);" does not terminate the process. Call _exit()
explicitly, in this case (rather than exit(), because the terminating
kill() calls do not call the functions registered with atexit() either).
ps/output.c: Always null-terminate outbuf in show_one_proc().
Before "strlen(outbuf)", if one of the pr_*() functions forgot to do it.
This prevents an out-of-bounds read in strlen(), and an out-of-bounds
write in "outbuf[sz] = '\n'". Another solution would be to replace
strlen() with strnlen(), but this is not used anywhere else in the
code-base and may not exist in all libc's.
ps/output.c: Protect outbuf in various pr_*() functions.
pr_bsdstart(): Replace "strcpy(outbuf," with "snprintf(outbuf, COLWID,"
(which is used in all surrounding functions). (side note: the fact that
many pr_*() functions simply return "snprintf(outbuf, COLWID," justifies
the "amount" checks added to show_one_proc() by the "ps/output.c:
Replace strcpy() with snprintf() in show_one_proc()." patch)
pr_stime(): Check the return value of strftime() (in case of an error,
"the contents of the array are undefined").
help_pr_sig(): Handle the "len < 8" case, otherwise "sig+len-8" may
point outside the sig string.
pr_context(): Handle the empty string case, or else "outbuf[len-1]"
points outside outbuf.
ps/output.c: Enforce a safe range for max_rightward.
Enforce a maximum max_rightward of OUTBUF_SIZE-1, because it is used in
constructs such as "snprintf(outbuf, max_rightward+1," (we could remove
the extra check at the beginning of forest_helper() now, but we decided
to leave it, as a precaution and reminder).
The minimum max_rightward check is not strictly needed, because it is
unsigned. However, we decided to add it anyway:
- most of the other variables are signed;
- make it visually clear that this case is properly handled;
- ideally, the minimum max_rightward should be 1, not 0 (to prevent
integer overflows such as "max_rightward-1"), but this might change
the behavior/output of ps, so we decided against it, for now.
Instead, we fixed the only function that overflows if max_rightward is
0. Also, enforce the same safe range for max_leftward, although it is
never used throughout the code-base.
1/ Do not go deeper than the size of forest_prefix[], to prevent a
buffer overflow (sizeof(forest_prefix) is roughly 128K, but the maximum
/proc/sys/kernel/pid_max is 4M). (actually, we go deeper, but we stop
adding bytes to forest_prefix[])
2/ Always null-terminate forest_prefix[] at the current level.
May happen if strlen(src) > INT_MAX for example. This patch prevents
escaped_copy() from increasing maxroom and returning -1 (= number of
bytes consumed in dst).
proc/escape.c: Prevent buffer overflows in escape_command().
This solves several problems:
1/ outbuf[1] was written to, but not outbuf[0], which was left
uninitialized (well, SECURE_ESCAPE_ARGS() already fixes this, but do it
explicitly as well); we know it is safe to write one byte to outbuf,
because SECURE_ESCAPE_ARGS() guarantees it.
2/ If bytes was 1, the write to outbuf[1] was an off-by-one overflow.
3/ Do not call escape_str() with a 0 bufsize if bytes == overhead.
4/ Prevent various buffer overflows if bytes <= overhead.
projects / procps-ng / log