2022-01-13 01:11:10

by Kees Cook

[permalink] [raw]
Subject: [PATCH v3] crypto: octeontx2 - Avoid stack variable overflow

Building with -Warray-bounds showed a stack variable array index
overflow. Increase the expected size of the array to avoid the warning:

In file included from ./include/linux/printk.h:555,
from ./include/asm-generic/bug.h:22,
from ./arch/x86/include/asm/bug.h:84,
from ./include/linux/bug.h:5,
from ./include/linux/mmdebug.h:5,
from ./include/linux/gfp.h:5,
from ./include/linux/firmware.h:7,
from drivers/crypto/marvell/octeontx2/otx2_cptpf_ucode.c:5:
drivers/crypto/marvell/octeontx2/otx2_cptpf_ucode.c: In function 'otx2_cpt_print_uc_dbg_info':
./include/linux/dynamic_debug.h:162:33: warning: array subscript 4 is above array bounds of 'u32[4]' {aka 'unsigned int[4]'} [-Warray-bounds]
162 | _dynamic_func_call(fmt, __dynamic_pr_debug, \
| ^
./include/linux/dynamic_debug.h:134:17: note: in definition of macro '__dynamic_func_call'
134 | func(&id, ##__VA_ARGS__); \
| ^~~~
./include/linux/dynamic_debug.h:162:9: note: in expansion of macro '_dynamic_func_call'
162 | _dynamic_func_call(fmt, __dynamic_pr_debug, \
| ^~~~~~~~~~~~~~~~~~
./include/linux/printk.h:570:9: note: in expansion of macro 'dynamic_pr_debug'
570 | dynamic_pr_debug(fmt, ##__VA_ARGS__)
| ^~~~~~~~~~~~~~~~
drivers/crypto/marvell/octeontx2/otx2_cptpf_ucode.c:1807:41: note: in expansion of macro 'pr_debug'
1807 | pr_debug("Mask: %8.8x %8.8x %8.8x %8.8x %8.8x",
| ^~~~~~~~
drivers/crypto/marvell/octeontx2/otx2_cptpf_ucode.c:1765:13: note: while referencing 'mask'
1765 | u32 mask[4];
| ^~~~

This is justified because the mask size (eng_grps->engs_num) can be at
most 144 (OTX2_CPT_MAX_ENGINES bits), which is larger than available
storage. 4 * 32 == 128, so this must be 5: 5 * 32bit = 160.

Additionally clear the mask before conversion so trailing bits are zero.

Cc: Herbert Xu <[email protected]>
Cc: Boris Brezillon <[email protected]>
Cc: Arnaud Ebalard <[email protected]>
Cc: Srujana Challa <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Suheil Chandran <[email protected]>
Cc: Shijith Thotton <[email protected]>
Cc: Lukasz Bartosik <[email protected]>
Cc: [email protected]
Fixes: d9d7749773e8 ("crypto: octeontx2 - add apis for custom engine groups")
Acked-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
---
v1: https://lore.kernel.org/lkml/[email protected]/
v2: https://lore.kernel.org/lkml/[email protected]/
v3:
- Fix commit log math typo
- Add Ack
---
drivers/crypto/marvell/octeontx2/otx2_cptpf_ucode.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/crypto/marvell/octeontx2/otx2_cptpf_ucode.c b/drivers/crypto/marvell/octeontx2/otx2_cptpf_ucode.c
index 4c8ebdf671ca..1b4d425bbf0e 100644
--- a/drivers/crypto/marvell/octeontx2/otx2_cptpf_ucode.c
+++ b/drivers/crypto/marvell/octeontx2/otx2_cptpf_ucode.c
@@ -1753,7 +1753,6 @@ void otx2_cpt_print_uc_dbg_info(struct otx2_cptpf_dev *cptpf)
char engs_info[2 * OTX2_CPT_NAME_LENGTH];
struct otx2_cpt_eng_grp_info *grp;
struct otx2_cpt_engs_rsvd *engs;
- u32 mask[4];
int i, j;

pr_debug("Engine groups global info");
@@ -1785,6 +1784,8 @@ void otx2_cpt_print_uc_dbg_info(struct otx2_cptpf_dev *cptpf)
for (j = 0; j < OTX2_CPT_MAX_ETYPES_PER_GRP; j++) {
engs = &grp->engs[j];
if (engs->type) {
+ u32 mask[5] = { };
+
get_engs_info(grp, engs_info,
2 * OTX2_CPT_NAME_LENGTH, j);
pr_debug("Slot%d: %s", j, engs_info);
--
2.30.2