From: Dmitry V. Levin <ldv@altlinux.org>
Date: Sun, 28 May 2017 17:13:29 +0000 (+0000)
Subject: signal: fix decoding of struct old_sigaction on some architectures
X-Git-Tag: v4.18~150
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=337d3a10ce29d778df75b3def3aa1ac6ccc4da2c;p=strace

signal: fix decoding of struct old_sigaction on some architectures

On alpha, struct old_sigaction.sa_flags has a 32-bit type.

On mips, only first word of old_sigaction.sa_mask is read.

On all architectures except alpha and mips that have old sigaction
syscall, struct old_sigaction has sa_restorer field that has to be
decoded.

* signal.c (struct old_sigaction) [ALPHA]: Change sa_flags type
to unsigned int, add ATTRIBUTE_PACKED.
[MIPS]: Dhrink sa_mask array to 1 element.
[!ALPHA && !MIPS]: Define sa_restorer field unconditionally.
(struct old_sigaction32): Likewise.
(decode_old_sigaction) [!current_wordsize]: Initialize sa_restorer field
from old_sigaction32.sa_restorer unconditionally.
[!ALPHA && !MIPS]: Print old_sigaction.sa_restorer if SA_RESTORER flag
is set.
* NEWS: Mention this change.
---

diff --git a/NEWS b/NEWS
index 20f8640f..8d0d4a5b 100644
--- a/NEWS
+++ b/NEWS
@@ -7,6 +7,7 @@ Noteworthy changes in release ?.?? (????-??-??)
   * strace no longer resets SIGCHLD handler in tracees to the default action.
   * When traced command is terminated by a blocked signal, strace unblocks
     that signal to ensure its own termination with the same signal.
+  * Fixed corner cases in decoding of old sigaction syscall.
 
 Noteworthy changes in release 4.17 (2017-05-24)
 ===============================================
diff --git a/signal.c b/signal.c
index c8b0a5f5..5f6650f2 100644
--- a/signal.c
+++ b/signal.c
@@ -300,29 +300,32 @@ SYS_FUNC(ssetmask)
 
 struct old_sigaction {
 	/* sa_handler may be a libc #define, need to use other name: */
-#ifdef MIPS
+#if defined MIPS
 	unsigned int sa_flags;
 	unsigned long sa_handler__;
-	/* Kernel treats sa_mask as an array of longs. */
-	unsigned long sa_mask[NSIG / sizeof(long)];
+	unsigned long sa_mask;
+#elif defined ALPHA
+	unsigned long sa_handler__;
+	unsigned long sa_mask;
+	unsigned int sa_flags;
 #else
 	unsigned long sa_handler__;
 	unsigned long sa_mask;
 	unsigned long sa_flags;
-#endif /* !MIPS */
-#if HAVE_SA_RESTORER
 	unsigned long sa_restorer;
 #endif
-};
+}
+#ifdef ALPHA
+	ATTRIBUTE_PACKED
+#endif
+;
 
 struct old_sigaction32 {
 	/* sa_handler may be a libc #define, need to use other name: */
 	uint32_t sa_handler__;
 	uint32_t sa_mask;
 	uint32_t sa_flags;
-#if HAVE_SA_RESTORER
 	uint32_t sa_restorer;
-#endif
 };
 
 static void
@@ -340,9 +343,7 @@ decode_old_sigaction(struct tcb *const tcp, const kernel_ulong_t addr)
 		memset(&sa, 0, sizeof(sa));
 		sa.sa_handler__ = sa32.sa_handler__;
 		sa.sa_flags = sa32.sa_flags;
-#if HAVE_SA_RESTORER && defined SA_RESTORER
 		sa.sa_restorer = sa32.sa_restorer;
-#endif
 		sa.sa_mask = sa32.sa_mask;
 	} else
 #endif
@@ -352,15 +353,11 @@ decode_old_sigaction(struct tcb *const tcp, const kernel_ulong_t addr)
 	tprints("{sa_handler=");
 	print_sa_handler(sa.sa_handler__);
 	tprints(", sa_mask=");
-#ifdef MIPS
-	tprintsigmask_addr("", sa.sa_mask);
-#else
 	tprintsigmask_val("", sa.sa_mask);
-#endif
 	tprints(", sa_flags=");
 	printflags(sigact_flags, sa.sa_flags, "SA_???");
-#if HAVE_SA_RESTORER && defined SA_RESTORER
-	if (sa.sa_flags & SA_RESTORER) {
+#if !(defined ALPHA || defined MIPS)
+	if (sa.sa_flags & 0x04000000U) {
 		tprints(", sa_restorer=");
 		printaddr(sa.sa_restorer);
 	}