| Message ID | 09db94615fe22e053d978e93e404c8a6ff64756d.1659350650.git.fweimer@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | Internal asserts cleanups | expand |
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)
* Adhemerval Zanella Netto via Libc-alpha: >> + 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. We should use a CAS here anyway because the earlier message is likely more valuable for debugging purposes. The exchange was needed because when __libc_message could continue execution in the old days, we had to somehow avoid the memory leak. That's no longer a concern with the current code. I will try to clean this up further. Thanks, Florian
On 02/08/22 05:03, Florian Weimer wrote: > * Adhemerval Zanella Netto via Libc-alpha: > >>> + 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. > > We should use a CAS here anyway because the earlier message is likely > more valuable for debugging purposes. The exchange was needed because > when __libc_message could continue execution in the old days, we had to > somehow avoid the memory leak. That's no longer a concern with the > current code. I will try to clean this up further. My intention was more to move away from old atomics macros and use compiler builtins when possible.
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); } } 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)
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. --- 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(-)