cdefs: Drop access attribute for _FORTIFY_SOURCE=3 (BZ #31383)

When passed a pointer to a zero-sized struct, the access attribute
without the third argument misleads -Wstringop-overflow diagnostics to
think that a function is writing 1 byte into the zero-sized structs.
The attribute doesn't add that much value in this context, so drop it
completely for _FORTIFY_SOURCE=3.

Resolves: BZ #31383
Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
index 6b03417453..2e8279a2c7 100644
--- a/misc/sys/cdefs.h
+++ b/misc/sys/cdefs.h
@@ -837,10 +837,10 @@ _Static_assert (0, "IEEE 128-bits long double requires redirection on this platf
 #  define __attr_access(x) __attribute__ ((__access__ x))
 /* For _FORTIFY_SOURCE == 3 we use __builtin_dynamic_object_size, which may
    use the access attribute to get object sizes from function definition
-   arguments, so we can't use them on functions we fortify.  Drop the object
-   size hints for such functions.  */
+   arguments, so we can't use them on functions we fortify.  Drop the access
+   attribute for such functions.  */
 #  if __USE_FORTIFY_LEVEL == 3
-#    define __fortified_attr_access(a, o, s) __attribute__ ((__access__ (a, o)))
+#    define __fortified_attr_access(a, o, s)
 #  else
 #    define __fortified_attr_access(a, o, s) __attr_access ((a, o, s))
 #  endif