From: "GONG, Ruiqi" gongruiqi1@huawei.com
[ Upstream commit a7ed3465daa240bdf01a5420f64336fee879c09d ]
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 gongruiqi1@huawei.com Reviewed-by: Gustavo A. R. Silva gustavoars@kernel.org Reviewed-by: Kees Cook keescook@chromium.org Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Sasha Levin sashal@kernel.org --- 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 a494cf43a7552..b0caad82b6937 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(/* no tag */, offsets, /* no attrs */, + /* 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 a09b2fc11c80e..c0389199c0dcb 100644 --- a/net/bridge/netfilter/ebtables.c +++ b/net/bridge/netfilter/ebtables.c @@ -2114,8 +2114,7 @@ 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(entry->offsets));
if (state->buf_kern_start) { buf_start = state->buf_kern_start + state->buf_kern_offset;