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Avoid accessing corrupted stack from __stack_chk_fail [BZ #21752]

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__libc_argv[0] points to address on stack and __libc_secure_getenv
accesses environment variables which are on stack.  We should avoid
accessing stack when stack is corrupted.

This patch also renames function argument in __fortify_fail_abort
from do_backtrace to need_backtrace to avoid confusion with do_backtrace
from enum __libc_message_action.

	[BZ #21752]
	* debug/fortify_fail.c (__fortify_fail_abort): Don't pass down
	__libc_argv[0] if we aren't doing backtrace.  Rename do_backtrace
	to need_backtrace.
	* sysdeps/posix/libc_fatal.c (__libc_message): Don't call
	__libc_secure_getenv if we aren't doing backtrace.
This commit is contained in:
H.J. Lu
2017-07-24 06:06:08 -07:00
parent 55703fcace
commit 422ff87c24
3 changed files with 27 additions and 9 deletions
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15
sysdeps/posix/libc_fatal.c
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@@ -75,11 +75,16 @@ __libc_message (enum __libc_message_action action, const char *fmt, ...)
FATAL_PREPARE;
#endif
/* Open a descriptor for /dev/tty unless the user explicitly
requests errors on standard error. */
const char *on_2 = __libc_secure_getenv ("LIBC_FATAL_STDERR_");
if (on_2 == NULL || *on_2 == '\0')
fd = open_not_cancel_2 (_PATH_TTY, O_RDWR | O_NOCTTY | O_NDELAY);
/* Don't call __libc_secure_getenv if we aren't doing backtrace, which
may access the corrupted stack. */
if ((action & do_backtrace))
{
/* Open a descriptor for /dev/tty unless the user explicitly
requests errors on standard error. */
const char *on_2 = __libc_secure_getenv ("LIBC_FATAL_STDERR_");
if (on_2 == NULL || *on_2 == '\0')
fd = open_not_cancel_2 (_PATH_TTY, O_RDWR | O_NOCTTY | O_NDELAY);
}
if (fd == -1)
fd = STDERR_FILENO;