| Message ID | ZN5WkbPelHUSTXOA@work (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 78d44b824ed04dd1553c55c5b839c9a55cbcaf4e |
| Headers | show |
| Series | [v3,next] cgroup: Avoid -Wstringop-overflow warnings | expand |
On Thu, Aug 17, 2023 at 11:19:13AM -0600, Gustavo A. R. Silva wrote: > Change the notation from pointer-to-array to pointer-to-pointer. > With this, we avoid the compiler complaining about trying > to access a region of size zero as an argument during function > calls. > > This is a workaround to prevent the compiler complaining about > accessing an array of size zero when evaluating the arguments > of a couple of function calls. See below: > > kernel/cgroup/cgroup.c: In function 'find_css_set': > kernel/cgroup/cgroup.c:1206:16: warning: 'find_existing_css_set' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] > 1206 | cset = find_existing_css_set(old_cset, cgrp, template); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > kernel/cgroup/cgroup.c:1206:16: note: referencing argument 3 of type 'struct cgroup_subsys_state *[0]' > kernel/cgroup/cgroup.c:1071:24: note: in a call to function 'find_existing_css_set' > 1071 | static struct css_set *find_existing_css_set(struct css_set *old_cset, > | ^~~~~~~~~~~~~~~~~~~~~ > > With the change to pointer-to-pointer, the functions are not prevented > from being executed, and they will do what they have to do when > CGROUP_SUBSYS_COUNT == 0. > > Address the following -Wstringop-overflow warnings seen when > built with ARM architecture and aspeed_g4_defconfig configuration > (notice that under this configuration CGROUP_SUBSYS_COUNT == 0): > > kernel/cgroup/cgroup.c:1208:16: warning: 'find_existing_css_set' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] > kernel/cgroup/cgroup.c:1258:15: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] > kernel/cgroup/cgroup.c:6089:18: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] > kernel/cgroup/cgroup.c:6153:18: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] > > This results in no differences in binary output. > > Link: https://github.com/KSPP/linux/issues/316 > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org>
On Thu, Aug 17, 2023 at 11:19:13AM -0600, Gustavo A. R. Silva wrote: > Change the notation from pointer-to-array to pointer-to-pointer. > With this, we avoid the compiler complaining about trying > to access a region of size zero as an argument during function > calls. > > This is a workaround to prevent the compiler complaining about > accessing an array of size zero when evaluating the arguments > of a couple of function calls. See below: > > kernel/cgroup/cgroup.c: In function 'find_css_set': > kernel/cgroup/cgroup.c:1206:16: warning: 'find_existing_css_set' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] > 1206 | cset = find_existing_css_set(old_cset, cgrp, template); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > kernel/cgroup/cgroup.c:1206:16: note: referencing argument 3 of type 'struct cgroup_subsys_state *[0]' > kernel/cgroup/cgroup.c:1071:24: note: in a call to function 'find_existing_css_set' > 1071 | static struct css_set *find_existing_css_set(struct css_set *old_cset, > | ^~~~~~~~~~~~~~~~~~~~~ > > With the change to pointer-to-pointer, the functions are not prevented > from being executed, and they will do what they have to do when > CGROUP_SUBSYS_COUNT == 0. > > Address the following -Wstringop-overflow warnings seen when > built with ARM architecture and aspeed_g4_defconfig configuration > (notice that under this configuration CGROUP_SUBSYS_COUNT == 0): > > kernel/cgroup/cgroup.c:1208:16: warning: 'find_existing_css_set' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] > kernel/cgroup/cgroup.c:1258:15: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] > kernel/cgroup/cgroup.c:6089:18: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] > kernel/cgroup/cgroup.c:6153:18: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] > > This results in no differences in binary output. > > Link: https://github.com/KSPP/linux/issues/316 > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Applied to cgroup/for-6.6. Thanks.
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index ccbbba06da5b..68e2d9812e3f 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -929,7 +929,7 @@ static void css_set_move_task(struct task_struct *task, #define CSS_SET_HASH_BITS 7 static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); -static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) +static unsigned long css_set_hash(struct cgroup_subsys_state **css) { unsigned long key = 0UL; struct cgroup_subsys *ss; @@ -1070,7 +1070,7 @@ static bool compare_css_sets(struct css_set *cset, */ static struct css_set *find_existing_css_set(struct css_set *old_cset, struct cgroup *cgrp, - struct cgroup_subsys_state *template[]) + struct cgroup_subsys_state **template) { struct cgroup_root *root = cgrp->root; struct cgroup_subsys *ss;
Change the notation from pointer-to-array to pointer-to-pointer. With this, we avoid the compiler complaining about trying to access a region of size zero as an argument during function calls. This is a workaround to prevent the compiler complaining about accessing an array of size zero when evaluating the arguments of a couple of function calls. See below: kernel/cgroup/cgroup.c: In function 'find_css_set': kernel/cgroup/cgroup.c:1206:16: warning: 'find_existing_css_set' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] 1206 | cset = find_existing_css_set(old_cset, cgrp, template); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/cgroup/cgroup.c:1206:16: note: referencing argument 3 of type 'struct cgroup_subsys_state *[0]' kernel/cgroup/cgroup.c:1071:24: note: in a call to function 'find_existing_css_set' 1071 | static struct css_set *find_existing_css_set(struct css_set *old_cset, | ^~~~~~~~~~~~~~~~~~~~~ With the change to pointer-to-pointer, the functions are not prevented from being executed, and they will do what they have to do when CGROUP_SUBSYS_COUNT == 0. Address the following -Wstringop-overflow warnings seen when built with ARM architecture and aspeed_g4_defconfig configuration (notice that under this configuration CGROUP_SUBSYS_COUNT == 0): kernel/cgroup/cgroup.c:1208:16: warning: 'find_existing_css_set' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] kernel/cgroup/cgroup.c:1258:15: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] kernel/cgroup/cgroup.c:6089:18: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] kernel/cgroup/cgroup.c:6153:18: warning: 'css_set_hash' accessing 4 bytes in a region of size 0 [-Wstringop-overflow=] This results in no differences in binary output. Link: https://github.com/KSPP/linux/issues/316 Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> --- Changes in v3: - Update changelog text to point out that this is a workaround. Changes in v2: - Use pointer-to-pointer instead of pointer-to-array. - Update changelog text. - Link: https://lore.kernel.org/linux-hardening/ZN02iLcZYgxHFrEN@work/ v1: - Link: https://lore.kernel.org/linux-hardening/ZIpm3pcs3iCP9UaR@work/ kernel/cgroup/cgroup.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)