parse_fdinfo: Don't advance pointer twice [BZ #31798]

pidfd_getpid.c has

      /* Ignore invalid large values.  */
      if (INT_MULTIPLY_WRAPV (10, n, &n)
          || INT_ADD_WRAPV (n, *l++ - '0', &n))
        return -1;

For GCC older than GCC 7, INT_ADD_WRAPV(a, b, r) is defined as

   _GL_INT_OP_WRAPV (a, b, r, +, _GL_INT_ADD_RANGE_OVERFLOW)

and *l++ - '0' is evaluated twice.  Fix BZ #31798 by moving "l++" out of
the if statement.  Tested with GCC 6.4 and GCC 14.1.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

diff --git a/sysdeps/unix/sysv/linux/pidfd_getpid.c b/sysdeps/unix/sysv/linux/pidfd_getpid.c
index ebcbe8fdf6e2d3dac0b9a7d9aa2ce08f2ebc998b..6967477fabde355eda15759832e6fb3140ecd6be 100644 (file)
--- a/sysdeps/unix/sysv/linux/pidfd_getpid.c
+++ b/sysdeps/unix/sysv/linux/pidfd_getpid.c
@@ -74,8 +74,10 @@ parse_fdinfo (const char *l, void *arg)
 
       /* Ignore invalid large values.  */
       if (INT_MULTIPLY_WRAPV (10, n, &n)
-          || INT_ADD_WRAPV (n, *l++ - '0', &n))
+          || INT_ADD_WRAPV (n, *l - '0', &n))
         return -1;
+
+      l++;
     }
 
   /* -1 indicates that the process is terminated.  */