keyctl: use printstr_ex for printing out buffer

keyctl_read_key had subtle bug by treating out buffer in KEYCTL_READ
as NUL-terminated, which is not true.  We fix it by adding parameter to
keyctl_read_key signalising whether buffer is NUL-terminated and using
printstr_ex for printing (expectedly) NUL-terminated strings.

* keyctl.c (keyctl_read_key): Add has_nul parameter.  Do not use -1 as
string len.  Use printstr_ex for buffer output with user style depending
on has_nul value.
(SYS_FUNC(keyctl)): Specify has_nul parameter to keyctl_read_key
by comparing cmd value with KEYCTL_READ.

diff --git a/keyctl.c b/keyctl.c
index 536fa8055d192d4e0ac8e15c7d0dbf317d78f4a0..73f976624d7c3e2a071fce55ae4801dcd0a35031 100644 (file)
--- a/keyctl.c
+++ b/keyctl.c
@@ -108,7 +108,8 @@ keyctl_handle_key_key(struct tcb *tcp, key_serial_t id1, key_serial_t id2)
 }
 
 static void
-keyctl_read_key(struct tcb *tcp, key_serial_t id, long addr, long len)
+keyctl_read_key(struct tcb *tcp, key_serial_t id, long addr, long len,
+               bool has_nul)
 {
        if (entering(tcp)) {
                print_keyring_serial_number(id);
@@ -118,8 +119,9 @@ keyctl_read_key(struct tcb *tcp, key_serial_t id, long addr, long len)
                        printaddr(addr);
                else {
                        long rval = tcp->u_rval > len ?
-                                   len : (tcp->u_rval ? -1 : 0);
-                       printstr(tcp, addr, rval);
+                                   len : tcp->u_rval;
+                       printstr_ex(tcp, addr, rval, has_nul ?
+                                   QUOTE_OMIT_TRAILING_0 : 0);
                }
                tprintf(", %lu", len);
        }
@@ -301,7 +303,8 @@ SYS_FUNC(keyctl)
        case KEYCTL_READ:
        case KEYCTL_GET_SECURITY:
                keyctl_read_key(tcp, tcp->u_arg[1],
-                               tcp->u_arg[2], tcp->u_arg[3]);
+                               tcp->u_arg[2], tcp->u_arg[3],
+                               cmd != KEYCTL_READ);
                return 0;
 
        case KEYCTL_SEARCH: