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dlfcn: Guard __dlerror_main_freeres with __libc_once_get (once) [BZ#24476]

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dlerror.c (__dlerror_main_freeres) will try to free resources which only
have been initialized when init () has been called. That function is
called when resources are needed using __libc_once (once, init) where
once is a __libc_once_define (static, once) in the dlerror.c file.
Trying to free those resources if init () hasn't been called will
produce errors under valgrind memcheck. So guard the freeing of those
resources using __libc_once_get (once) and make sure we have a valid
key. Also add a similar guard to __dlerror ().

	* dlfcn/dlerror.c (__dlerror_main_freeres): Guard using
	__libc_once_get (once) and static_bug == NULL.
	(__dlerror): Check we have a valid key, set result to static_buf
	otherwise.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
(cherry picked from commit 11b451c886)
This commit is contained in:
Mark Wielaard 2019-05-15 17:14:01 +02:00
parent d948478bc5
commit 059d6750f9
3 changed files with 30 additions and 8 deletions
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8
ChangeLog
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@ -1,3 +1,11 @@
2019-05-15 Mark Wielaard <mark@klomp.org>
[BZ#24476]
* dlfcn/dlerror.c (__dlerror_main_freeres): Guard using
__libc_once_get (once) and static_buf == NULL.
(__dlerror): Check we have a valid key, set result to static_buf
otherwise.
2019-05-15 Andreas Schwab <schwab@suse.de>
[BZ #20568]

1
NEWS
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@ -58,6 +58,7 @@ The following bugs are resolved with this release:
[24097] Can't use 64-bit register for size_t in assembly codes for x32 (CVE-2019-6488)
[24155] x32 memcmp can treat positive length as 0 (if sign bit in RDX is set) (CVE-2019-7309)
[24161] __run_fork_handlers self-deadlocks in malloc/tst-mallocfork2
[24476] dlfcn: Guard __dlerror_main_freeres with __libc_once_get (once)
Security related changes:

29
dlfcn/dlerror.c
View File

@ -72,9 +72,16 @@ __dlerror (void)
__libc_once (once, init);
/* Get error string. */
result = (struct dl_action_result *) __libc_getspecific (key);
if (result == NULL)
result = &last_result;
if (static_buf != NULL)
result = static_buf;
else
{
/* init () has been run and we don't use the static buffer.
So we have a valid key. */
result = (struct dl_action_result *) __libc_getspecific (key);
if (result == NULL)
result = &last_result;
}
/* Test whether we already returned the string. */
if (result->returned != 0)
@ -230,13 +237,19 @@ free_key_mem (void *mem)
void
__dlerror_main_freeres (void)
{
void *mem;
/* Free the global memory if used. */
check_free (&last_result);
/* Free the TSD memory if used. */
mem = __libc_getspecific (key);
if (mem != NULL)
free_key_mem (mem);
if (__libc_once_get (once) && static_buf == NULL)
{
/* init () has been run and we don't use the static buffer.
So we have a valid key. */
void *mem;
/* Free the TSD memory if used. */
mem = __libc_getspecific (key);
if (mem != NULL)
free_key_mem (mem);
}
}
struct dlfcn_hook *_dlfcn_hook __attribute__((nocommon));