[PATCH] assert.c: Undefine _FORTIFY_SOURCE [BZ 32456]

[Sam James]

Sam James <sam@gentoo.org> writes:

> Florian Weimer <fweimer@redhat.com> writes:
>
>> * H. J. Lu:
>>
>>> When _FORTIFY_SOURCE is defined to >= 1, __printf_buffer, which is
>>> called with (mode_flags & PRINTF_FORTIFY) != 0 via assert (), calls
>>> __readonly_area to check if the format string is readonly.  The
>>> readonly check will fail in 2 cases:
>>> 1. When the message is translated and re-encoded, the format string
>>> is writable.
>>> 2. When fopen on /proc/self/maps returns NULL due to the malloc
>>> failure, as in test-assert-2.c, __readonly_area return -1.
>>> This triggers the fortification error:
>>>
>>>   if (readonly_format < 0)
>>>     __libc_fatal ("*** %n in writable segment detected ***\n");
>>>
>>> Undefine _FORTIFY_SOURCE to fix BZ 32456.
>>>
>>> Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
>>> ---
>>>  assert/assert.c | 15 +++++++++++++++
>>>  1 file changed, 15 insertions(+)
>>>
>>> diff --git a/assert/assert.c b/assert/assert.c
>>> index 47b06ec7fd..5446bbde52 100644
>>> --- a/assert/assert.c
>>> +++ b/assert/assert.c
>>> @@ -15,6 +15,21 @@
>>>     License along with the GNU C Library; if not, see
>>>     <https://www.gnu.org/licenses/>.  */
>>>  
>>> +/* When _FORTIFY_SOURCE is defined to >= 1, __printf_buffer, which is
>>> +   called with (mode_flags & PRINTF_FORTIFY) != 0 via assert (), calls
>>> +   __readonly_area to check if the format string is readonly.  The
>>> +   readonly check will fail in 2 cases:
>>> +   1. When the message is translated and re-encoded, the format string
>>> +   is writable.
>>> +   2. When fopen on /proc/self/maps returns NULL due to the malloc
>>> +   failure, as in test-assert-2.c, __readonly_area return -1.
>>> +   This triggers the fortification error:
>>> +
>>> +     if (readonly_format < 0)
>>> +       __libc_fatal ("*** %n in writable segment detected ***\n");
>>> +
>>> +   Undefine _FORTIFY_SOURCE to avoid this error.  */
>>> +#undef _FORTIFY_SOURCE
>>>  #include <assert.h>
>>>  #include <atomic.h>
>>>  #include <ldsodefs.h>
>>
>> Please see this parallel thread;
>>
>>   [PATCH] assert: Remove the use of %n from __assert_fail_base (BZ #32456)
>>   <https://inbox.sourceware.org/libc-alpha/20241230163153.2399453-1-adhemerval.zanella@linaro.org/>
>
> I'd personally like it if this went in for now so we can carry on our
> testing pre-release without the noise of a (known) test failure.

Nevermind, I see 6f0ea84f17581d13ad668adbc181c37141d389b8 landed.