| Message ID | 20230808133038.771316-1-gongruiqi@huaweicloud.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] netfilter: ebtables: fix fortify warnings | expand |
On August 8, 2023 9:32:50 AM PDT, "Gustavo A. R. Silva" <gustavoars@kernel.org> wrote: >On Tue, Aug 08, 2023 at 09:30:38PM +0800, GONG, Ruiqi wrote: >> From: "GONG, Ruiqi" <gongruiqi1@huawei.com> >> >> 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> >> --- >> >> v2: fix HDRTEST error by replacing struct_group() with __struct_group(), >> since it's a uapi header. >> >> 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..b0caad82b693 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)))); While we're here, can we drop this [0] in favor of []? -Kees >> }; >> >> 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])); > ^^^^^^^^^^^^ >You now can replace this ____________________________________| >with just `sizeof(entry->offsets)` > >With that change you can add my >Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> > >Thank you >-- >Gustavo > >> >> if (state->buf_kern_start) { >> buf_start = state->buf_kern_start + state->buf_kern_offset; >> -- >> 2.41.0 >>
On August 8, 2023 9:32:50 AM PDT, "Gustavo A. R. Silva" <gustavoars@kernel.org> wrote: >On Tue, Aug 08, 2023 at 09:30:38PM +0800, GONG, Ruiqi wrote: >> From: "GONG, Ruiqi" <gongruiqi1@huawei.com> >> >> 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> >> --- >> >> v2: fix HDRTEST error by replacing struct_group() with __struct_group(), >> since it's a uapi header. >> >> 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..b0caad82b693 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)))); >> }; Actually, looking at what size_entry_mwt() is doing, I think you probably DO want a tag for this and to use a real structure for the manipulations instead of doing array indexing? I dunno. This is a weird function! :) -Kees >> >> 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])); > ^^^^^^^^^^^^ >You now can replace this ____________________________________| >with just `sizeof(entry->offsets)` > >With that change you can add my >Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> > >Thank you >-- >Gustavo > >> >> if (state->buf_kern_start) { >> buf_start = state->buf_kern_start + state->buf_kern_offset; >> -- >> 2.41.0 >>
On 2023/08/09 0:32, Gustavo A. R. Silva wrote: > > [...] > >> 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])); > ^^^^^^^^^^^^ > You now can replace this ____________________________________| > with just `sizeof(entry->offsets)` > > With that change you can add my > Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> > > Thank you > -- > Gustavo > Will do. Thanks for the suggestion & review! >> >> if (state->buf_kern_start) { >> buf_start = state->buf_kern_start + state->buf_kern_offset; >> -- >> 2.41.0 >>
On 2023/08/09 6:53, Kees Cook wrote: > > [...] >>> >>> diff --git a/include/uapi/linux/netfilter_bridge/ebtables.h b/include/uapi/linux/netfilter_bridge/ebtables.h >>> index a494cf43a755..b0caad82b693 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)))); > > While we're here, can we drop this [0] in favor of []? > > -Kees > Look like it could be done. Will do in v3. Thanks! >>> }; >>> >>> 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])); >> ^^^^^^^^^^^^ >> You now can replace this ____________________________________| >> with just `sizeof(entry->offsets)` >> >> With that change you can add my >> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> >> >> Thank you >> -- >> Gustavo >> >>> >>> if (state->buf_kern_start) { >>> buf_start = state->buf_kern_start + state->buf_kern_offset; >>> -- >>> 2.41.0 >>> > >
On 2023/08/09 6:53, Kees Cook wrote: > > [...] >>> >>> diff --git a/include/uapi/linux/netfilter_bridge/ebtables.h b/include/uapi/linux/netfilter_bridge/ebtables.h >>> index a494cf43a755..b0caad82b693 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)))); > > While we're here, can we drop this [0] in favor of []? > > -Kees > There are still quite a lot of zero-element array in include/uapi/linux/netfilter_bridge/ebtables.h. I will submit another patch to change them altogether. >>> }; >>> >>> 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])); >> ^^^^^^^^^^^^ >> You now can replace this ____________________________________| >> with just `sizeof(entry->offsets)` >> >> With that change you can add my >> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> >> >> Thank you >> -- >> Gustavo >> >>> >>> if (state->buf_kern_start) { >>> buf_start = state->buf_kern_start + state->buf_kern_offset; >>> -- >>> 2.41.0 >>> > >
diff --git a/include/uapi/linux/netfilter_bridge/ebtables.h b/include/uapi/linux/netfilter_bridge/ebtables.h index a494cf43a755..b0caad82b693 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 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;