[PATCH 1/3] stdio: Clean up __libc_message after unconditional abort
Adhemerval Zanella Netto
adhemerval.zanella@linaro.org
Mon Aug 1 19:59:54 GMT 2022
On 01/08/22 07:45, Florian Weimer via Libc-alpha wrote:
> Since commit ec2c1fcefb200c6cb7e09553f3c6af8815013d83 ("malloc:
> Abort on heap corruption, without a backtrace [BZ #21754]"),
> __libc_message always terminates the process. Since commit
> a289ea09ea843ced6e5277c2f2e63c357bc7f9a3 ("Do not print backtraces
> on fatal glibc errors"), the backtrace facility has been removed.
> Therefore, remove enum __libc_message_action and the action
> argument of __libc_message, and mark __libc_message as _No_return.
LGTM, just a comment below.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> debug/fortify_fail.c | 4 +---
> include/stdio.h | 9 +-------
> malloc/malloc.c | 5 ++--
> sysdeps/posix/libc_fatal.c | 47 +++++++++++++++++---------------------
> 4 files changed, 25 insertions(+), 40 deletions(-)
>
> diff --git a/debug/fortify_fail.c b/debug/fortify_fail.c
> index b1c51662b7..b880f82cb6 100644
> --- a/debug/fortify_fail.c
> +++ b/debug/fortify_fail.c
> @@ -21,8 +21,6 @@ void
> __attribute__ ((noreturn))
> __fortify_fail (const char *msg)
> {
> - /* The loop is added only to keep gcc happy. */
> - while (1)
> - __libc_message (do_abort, "*** %s ***: terminated\n", msg);
> + __libc_message ("*** %s ***: terminated\n", msg);
> }
> libc_hidden_def (__fortify_fail)
> diff --git a/include/stdio.h b/include/stdio.h
> index a6f7fd43cb..c3e772ad9a 100644
> --- a/include/stdio.h
> +++ b/include/stdio.h
> @@ -143,18 +143,11 @@ extern int __gen_tempname (char *__tmpl, int __suffixlen, int __flags,
> # define __GT_DIR 1 /* create a directory */
> # define __GT_NOCREATE 2 /* just find a name not currently in use */
>
> -enum __libc_message_action
> -{
> - do_message = 0, /* Print message. */
> - do_abort = 1 << 0, /* Abort. */
> -};
> -
> /* Print out MESSAGE (which should end with a newline) on the error output
> and abort. */
> extern void __libc_fatal (const char *__message)
> __attribute__ ((__noreturn__));
> -extern void __libc_message (enum __libc_message_action action,
> - const char *__fnt, ...) attribute_hidden;
> +_Noreturn void __libc_message (const char *__fnt, ...) attribute_hidden;
> extern void __fortify_fail (const char *msg) __attribute__ ((__noreturn__));
> libc_hidden_proto (__fortify_fail)
>
> diff --git a/malloc/malloc.c b/malloc/malloc.c
> index bd3c76ed31..f3320d2663 100644
> --- a/malloc/malloc.c
> +++ b/malloc/malloc.c
> @@ -296,8 +296,7 @@ _Noreturn static void
> __malloc_assert (const char *assertion, const char *file, unsigned int line,
> const char *function)
> {
> - __libc_message (do_abort, "\
> -Fatal glibc error: malloc assertion failure in %s: %s\n",
> + __libc_message ("Fatal glibc error: malloc assertion failure in %s: %s\n",
> function, assertion);
> __builtin_unreachable ();
> }
> @@ -5657,7 +5656,7 @@ static void
> malloc_printerr (const char *str)
> {
> #if IS_IN (libc)
> - __libc_message (do_abort, "%s\n", str);
> + __libc_message ("%s\n", str);
> #else
> __libc_fatal (str);
> #endif
> diff --git a/sysdeps/posix/libc_fatal.c b/sysdeps/posix/libc_fatal.c
> index 2ee0010b8d..270238495d 100644
> --- a/sysdeps/posix/libc_fatal.c
> +++ b/sysdeps/posix/libc_fatal.c
> @@ -54,7 +54,7 @@ struct str_list
>
> /* Abort with an error message. */
> void
> -__libc_message (enum __libc_message_action action, const char *fmt, ...)
> +__libc_message (const char *fmt, ...)
> {
> va_list ap;
> int fd = -1;
> @@ -123,36 +123,31 @@ __libc_message (enum __libc_message_action action, const char *fmt, ...)
>
> WRITEV_FOR_FATAL (fd, iov, nlist, total);
>
> - if ((action & do_abort))
> + total = (total + 1 + GLRO(dl_pagesize) - 1) & ~(GLRO(dl_pagesize) - 1);
> + struct abort_msg_s *buf = __mmap (NULL, total,
> + PROT_READ | PROT_WRITE,
> + MAP_ANON | MAP_PRIVATE, -1, 0);
> + if (__glibc_likely (buf != MAP_FAILED))
> {
> - total = ((total + 1 + GLRO(dl_pagesize) - 1)
> - & ~(GLRO(dl_pagesize) - 1));
> - struct abort_msg_s *buf = __mmap (NULL, total,
> - PROT_READ | PROT_WRITE,
> - MAP_ANON | MAP_PRIVATE, -1, 0);
> - if (__glibc_likely (buf != MAP_FAILED))
> - {
> - buf->size = total;
> - char *wp = buf->msg;
> - for (int cnt = 0; cnt < nlist; ++cnt)
> - wp = mempcpy (wp, iov[cnt].iov_base, iov[cnt].iov_len);
> - *wp = '\0';
> -
> - /* We have to free the old buffer since the application might
> - catch the SIGABRT signal. */
> - struct abort_msg_s *old = atomic_exchange_acq (&__abort_msg,
> - buf);
> - if (old != NULL)
> - __munmap (old, old->size);
> - }
> + buf->size = total;
> + char *wp = buf->msg;
> + for (int cnt = 0; cnt < nlist; ++cnt)
> + wp = mempcpy (wp, iov[cnt].iov_base, iov[cnt].iov_len);
> + *wp = '\0';
> +
> + /* We have to free the old buffer since the application might
> + catch the SIGABRT signal. */
> + struct abort_msg_s *old = atomic_exchange_acq (&__abort_msg,
> + buf);
> + if (old != NULL)
> + __munmap (old, old->size);
I am aware that this is just replicating the code already in place, but maybe
replace the old atomic with atomic_exchange_acquire here.
> }
> }
>
> va_end (ap);
>
> - if ((action & do_abort))
> - /* Kill the application. */
> - abort ();
> + /* Kill the application. */
> + abort ();
> }
>
>
> @@ -161,6 +156,6 @@ __libc_fatal (const char *message)
> {
> /* The loop is added only to keep gcc happy. */
> while (1)
> - __libc_message (do_abort, "%s", message);
> + __libc_message ("%s", message);
> }
> libc_hidden_def (__libc_fatal)
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