The trailing array member of struct tx_buf was defined as a 1-element
array, but used as a flexible array. This was resulting in build warnings:
In function 'fortify_memset_chk',
inlined from 'memset_io' at /kisskb/src/arch/mips/include/asm/io.h:486:2,
inlined from 'build_auth_frame' at /kisskb/src/drivers/net/wireless/legacy/ray_cs.c:2697:2:
/kisskb/src/include/linux/fortify-string.h:493:25: error: call to '__write_overflow_field' declared with attribute warning:
detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
493 | __write_overflow_field(p_size_field, size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Replace it with an actual flexible array. Binary difference comparison
shows a single change in output:
│ drivers/net/wireless/legacy/ray_cs.c:883
│ lea 0x1c(%rbp),%r13d
│ - cmp $0x7c3,%r13d
│ + cmp $0x7c4,%r13d
This is from:
if (len + TX_HEADER_LENGTH > TX_BUF_SIZE) {
specifically:
#define TX_BUF_SIZE (2048 - sizeof(struct tx_msg))
This appears to have been originally buggy, so the change is correct.
Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Closes: https://lore.kernel.org/all/88f83d73-781d-bdc-126-aa629cb368c@xxxxxxxxxxxxxx
Cc: Kalle Valo <kvalo@xxxxxxxxxx>
Cc: linux-wireless@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
drivers/net/wireless/legacy/rayctl.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/wireless/legacy/rayctl.h b/drivers/net/wireless/legacy/rayctl.h
index 2b0f332043d7..1f3bde8ac73d 100644
--- a/drivers/net/wireless/legacy/rayctl.h
+++ b/drivers/net/wireless/legacy/rayctl.h
@@ -577,7 +577,7 @@ struct tx_msg {
struct tib_structure tib;
struct phy_header phy;
struct mac_header mac;
- UCHAR var[1];
+ UCHAR var[];
};
/****** ECF Receive Control Structure (RCS) Area at Shared RAM offset 0x0800 */
--
2.34.1
