Re: [PATCH v3] Fix FORTIFY_SOURCE false positive

[Siddhesh Poyarekar <siddhesh@gotplt.org>]

On 2023-10-03 13:18, Volker Weißmann wrote:
> When -D_FORTIFY_SOURCE=2 was given during compilation,
> sprintf and similar functions will check if their
> first argument is in read-only memory and exit with
> *** %n in writable segment detected ***
> otherwise. To check if the memory is read-only, glibc
> reads frpm the file "/proc/self/maps". If opening this
> file fails due to too many open files (EMFILE), glibc
> will now ignore this error.
> 
> Fixes [BZ #30932]
> 
> Signed-off-by: Volker Weißmann <volker.weissmann@gmx.de>
> ---

Thanks!  LGTM.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

Adhemerval, could you please add this with your test case patch and send 
it as a series?  I can then review that too.

Thanks,
Sid

>   sysdeps/unix/sysv/linux/readonly-area.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/sysdeps/unix/sysv/linux/readonly-area.c b/sysdeps/unix/sysv/linux/readonly-area.c
> index edc68873f6..ba32372ebb 100644
> --- a/sysdeps/unix/sysv/linux/readonly-area.c
> +++ b/sysdeps/unix/sysv/linux/readonly-area.c
> @@ -42,7 +42,9 @@ __readonly_area (const char *ptr, size_t size)
>   	     to the /proc filesystem if it is set[ug]id.  There has
>   	     been no willingness to change this in the kernel so
>   	     far.  */
> -	  || errno == EACCES)
> +	  || errno == EACCES
> +	  /* Process has reached the maximum number of open files.  */
> +	  || errno == EMFILE)
>   	return 1;
>         return -1;
>       }
> --
> 2.42.0
>