readelf: Workaround stringop-truncation error
Commit Message
In function ‘strncpy’,
inlined from ‘print_ehdr’ at readelf.c:1175:4:
error: ‘__builtin_strncpy’ specified bound 512 equals destination size
[-Werror=stringop-truncation]
strncpy doesn't terminate the copied string if there is not enough
room. We compensate later by explicitly adding a zero terminator at
buf[sizeof (buf) - 1]. Normally gcc does see this, but with
-fsanitize=address there is too much (checking) code in between. But
it is actually better to not let strncpy do too much work, so
substract one from the size.
Signed-off-by: Mark Wielaard <mark@klomp.org>
---
src/ChangeLog | 4 ++++
src/readelf.c | 2 +-
2 files changed, 5 insertions(+), 1 deletion(-)
Comments
On Sat, Dec 04, 2021 at 10:15:04PM +0100, Mark Wielaard wrote:
> In function ‘strncpy’,
> inlined from ‘print_ehdr’ at readelf.c:1175:4:
> error: ‘__builtin_strncpy’ specified bound 512 equals destination size
> [-Werror=stringop-truncation]
>
> strncpy doesn't terminate the copied string if there is not enough
> room. We compensate later by explicitly adding a zero terminator at
> buf[sizeof (buf) - 1]. Normally gcc does see this, but with
> -fsanitize=address there is too much (checking) code in between. But
> it is actually better to not let strncpy do too much work, so
> substract one from the size.
Pushed,
Mark
@@ -1,3 +1,7 @@
+2021-12-04 Mark Wielaard <mark@klomp.org>
+
+ * readelf.c (print_ehdr): Pass sizeof (buf) - 1 to strncpy.
+
2021-10-20 John M Mellor-Crummey <johnmc@rice.edu>
* readelf.c (print_debug_line_section): Try to read
@@ -1172,7 +1172,7 @@ print_ehdr (Ebl *ebl, GElf_Ehdr *ehdr)
(uint32_t) shdr->sh_link);
else
{
- strncpy (buf, _(" ([0] not available)"), sizeof (buf));
+ strncpy (buf, _(" ([0] not available)"), sizeof (buf) - 1);
buf[sizeof (buf) - 1] = '\0';
}