From: "GONG, Ruiqi" <[email protected]>
When compiling with gcc 13 and CONFIG_FORTIFY_SOURCE=y, the following
warning appears:
In function ‘fortify_memcpy_chk’,
inlined from ‘size_entry_mwt’ at net/bridge/netfilter/ebtables.c:2118:2:
./include/linux/fortify-string.h:592:25: error: call to ‘__read_overflow2_field’
declared with attribute warning: detected read beyond size of field (2nd parameter);
maybe use struct_group()? [-Werror=attribute-warning]
592 | __read_overflow2_field(q_size_field, size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The compiler is complaining:
memcpy(&offsets[1], &entry->watchers_offset,
sizeof(offsets) - sizeof(offsets[0]));
where memcpy reads beyong &entry->watchers_offset to copy
{watchers,target,next}_offset altogether into offsets[]. Silence the
warning by wrapping these three up via struct_group().
Signed-off-by: GONG, Ruiqi <[email protected]>
---
include/uapi/linux/netfilter_bridge/ebtables.h | 14 ++++++++------
net/bridge/netfilter/ebtables.c | 3 +--
2 files changed, 9 insertions(+), 8 deletions(-)
diff --git a/include/uapi/linux/netfilter_bridge/ebtables.h b/include/uapi/linux/netfilter_bridge/ebtables.h
index a494cf43a755..e634da196d08 100644
--- a/include/uapi/linux/netfilter_bridge/ebtables.h
+++ b/include/uapi/linux/netfilter_bridge/ebtables.h
@@ -182,12 +182,14 @@ struct ebt_entry {
unsigned char sourcemsk[ETH_ALEN];
unsigned char destmac[ETH_ALEN];
unsigned char destmsk[ETH_ALEN];
- /* sizeof ebt_entry + matches */
- unsigned int watchers_offset;
- /* sizeof ebt_entry + matches + watchers */
- unsigned int target_offset;
- /* sizeof ebt_entry + matches + watchers + target */
- unsigned int next_offset;
+ struct_group(offsets,
+ /* sizeof ebt_entry + matches */
+ unsigned int watchers_offset;
+ /* sizeof ebt_entry + matches + watchers */
+ unsigned int target_offset;
+ /* sizeof ebt_entry + matches + watchers + target */
+ unsigned int next_offset;
+ );
unsigned char elems[0] __attribute__ ((aligned (__alignof__(struct ebt_replace))));
};
diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 757ec46fc45a..5ec66b1ebb64 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -2115,8 +2115,7 @@ static int size_entry_mwt(const struct ebt_entry *entry, const unsigned char *ba
return ret;
offsets[0] = sizeof(struct ebt_entry); /* matches come first */
- memcpy(&offsets[1], &entry->watchers_offset,
- sizeof(offsets) - sizeof(offsets[0]));
+ memcpy(&offsets[1], &entry->offsets, sizeof(offsets) - sizeof(offsets[0]));
if (state->buf_kern_start) {
buf_start = state->buf_kern_start + state->buf_kern_offset;
--
2.41.0
GONG, Ruiqi <[email protected]> wrote:
> From: "GONG, Ruiqi" <[email protected]>
>
> When compiling with gcc 13 and CONFIG_FORTIFY_SOURCE=y, the following
> warning appears:
>
> In function ‘fortify_memcpy_chk’,
> inlined from ‘size_entry_mwt’ at net/bridge/netfilter/ebtables.c:2118:2:
> ./include/linux/fortify-string.h:592:25: error: call to ‘__read_overflow2_field’
> declared with attribute warning: detected read beyond size of field (2nd parameter);
> maybe use struct_group()? [-Werror=attribute-warning]
> 592 | __read_overflow2_field(q_size_field, size);
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> The compiler is complaining:
>
> memcpy(&offsets[1], &entry->watchers_offset,
> sizeof(offsets) - sizeof(offsets[0]));
>
> where memcpy reads beyong &entry->watchers_offset to copy
> {watchers,target,next}_offset altogether into offsets[]. Silence the
> warning by wrapping these three up via struct_group().
>
> Signed-off-by: GONG, Ruiqi <[email protected]>
> ---
> include/uapi/linux/netfilter_bridge/ebtables.h | 14 ++++++++------
> net/bridge/netfilter/ebtables.c | 3 +--
> 2 files changed, 9 insertions(+), 8 deletions(-)
>
> diff --git a/include/uapi/linux/netfilter_bridge/ebtables.h b/include/uapi/linux/netfilter_bridge/ebtables.h
> index a494cf43a755..e634da196d08 100644
> --- a/include/uapi/linux/netfilter_bridge/ebtables.h
> +++ b/include/uapi/linux/netfilter_bridge/ebtables.h
> @@ -182,12 +182,14 @@ struct ebt_entry {
> unsigned char sourcemsk[ETH_ALEN];
> unsigned char destmac[ETH_ALEN];
> unsigned char destmsk[ETH_ALEN];
> - /* sizeof ebt_entry + matches */
> - unsigned int watchers_offset;
> - /* sizeof ebt_entry + matches + watchers */
> - unsigned int target_offset;
> - /* sizeof ebt_entry + matches + watchers + target */
> - unsigned int next_offset;
> + struct_group(offsets,
> + /* sizeof ebt_entry + matches */
This is an UAPI header, I think you need to use __struct_group here.
Hi Ruiqi,
kernel test robot noticed the following build errors:
[auto build test ERROR on linus/master]
[also build test ERROR on horms-ipvs/master v6.5-rc5 next-20230808]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/GONG-Ruiqi/netfilter-ebtables-fix-fortify-warnings/20230808-095125
base: linus/master
patch link: https://lore.kernel.org/r/20230808014821.241688-1-gongruiqi%40huaweicloud.com
patch subject: [PATCH] netfilter: ebtables: fix fortify warnings
config: i386-randconfig-r011-20230808 (https://download.01.org/0day-ci/archive/20230808/[email protected]/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce: (https://download.01.org/0day-ci/archive/20230808/[email protected]/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
All errors (new ones prefixed by >>):
In file included from <command-line>:
>> ./usr/include/linux/netfilter_bridge/ebtables.h:185:9: error: expected specifier-qualifier-list before 'struct_group'
185 | struct_group(offsets,
| ^~~~~~~~~~~~
./usr/include/linux/netfilter_bridge/ebtables.h: In function 'ebt_get_target':
>> ./usr/include/linux/netfilter_bridge/ebtables.h:199:57: error: 'struct ebt_entry' has no member named 'target_offset'
199 | return (struct ebt_entry_target *)((char *)e + e->target_offset);
| ^~
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
On 2023/08/08 23:54, Florian Westphal wrote:
>
> [...]
>>
>> diff --git a/include/uapi/linux/netfilter_bridge/ebtables.h b/include/uapi/linux/netfilter_bridge/ebtables.h
>> index a494cf43a755..e634da196d08 100644
>> --- a/include/uapi/linux/netfilter_bridge/ebtables.h
>> +++ b/include/uapi/linux/netfilter_bridge/ebtables.h
>> @@ -182,12 +182,14 @@ struct ebt_entry {
>> unsigned char sourcemsk[ETH_ALEN];
>> unsigned char destmac[ETH_ALEN];
>> unsigned char destmsk[ETH_ALEN];
>> - /* sizeof ebt_entry + matches */
>> - unsigned int watchers_offset;
>> - /* sizeof ebt_entry + matches + watchers */
>> - unsigned int target_offset;
>> - /* sizeof ebt_entry + matches + watchers + target */
>> - unsigned int next_offset;
>> + struct_group(offsets,
>> + /* sizeof ebt_entry + matches */
>
> This is an UAPI header, I think you need to use __struct_group here.
Thanks for the reminder! I've fixed it in v2:
https://lore.kernel.org/all/[email protected]/
Please review it :)