After commit 6f110a5e4f99 ("Disable SLUB_TINY for build testing"), which causes CONFIG_KASAN to be enabled in allmodconfig again, arm64 allmodconfig builds with older versions of clang (15 through 17) show an instance of -Wframe-larger-than (which breaks the build with CONFIG_WERROR=y):

drivers/staging/rtl8723bs/core/rtw_security.c:1287:5: error: stack frame size (2208) exceeds limit (2048) in 'rtw_aes_decrypt' [-Werror,-Wframe-larger-than] 1287 | u32 rtw_aes_decrypt(struct adapter *padapter, u8 *precvframe) | ^

This comes from aes_decipher() being inlined in rtw_aes_decrypt(). Running the same build with CONFIG_FRAME_WARN=128 shows aes_cipher() also uses a decent amount of stack, just under the limit of 2048:

drivers/staging/rtl8723bs/core/rtw_security.c:864:19: warning: stack frame size (1952) exceeds limit (128) in 'aes_cipher' [-Wframe-larger-than] 864 | static signed int aes_cipher(u8 *key, uint hdrlen, | ^

-Rpass-analysis=stack-frame-layout only shows one large structure on the stack, which is the ctx variable inlined from aes128k128d(). A good number of the other variables come from the additional checks of fortified string routines, which are present in memset(), which both aes_cipher() and aes_decipher() use to initialize some temporary buffers. In this case, since the size is known at compile time, these additional checks should not result in any code generation changes but allmodconfig has several sanitizers enabled, which may make it harder for the compiler to eliminate the compile time checks and the variables that come about from them.

The memset() calls are just initializing these buffers to zero, so use '= {}' instead, which is used all over the kernel and does the exact same thing as memset() without the fortify checks, which drops the stack usage of these functions by a few hundred kilobytes.

drivers/staging/rtl8723bs/core/rtw_security.c:864:19: warning: stack frame size (1584) exceeds limit (128) in 'aes_cipher' [-Wframe-larger-than] 864 | static signed int aes_cipher(u8 *key, uint hdrlen, | ^ drivers/staging/rtl8723bs/core/rtw_security.c:1271:5: warning: stack frame size (1456) exceeds limit (128) in 'rtw_aes_decrypt' [-Wframe-larger-than] 1271 | u32 rtw_aes_decrypt(struct adapter *padapter, u8 *precvframe) | ^

Cc: stable@vger.kernel.org Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver") Signed-off-by: Nathan Chancellor nathan@kernel.org --- drivers/staging/rtl8723bs/core/rtw_security.c | 44 +++++++++------------------ 1 file changed, 14 insertions(+), 30 deletions(-)

diff --git a/drivers/staging/rtl8723bs/core/rtw_security.c b/drivers/staging/rtl8723bs/core/rtw_security.c index 1e9eff01b1aa..e9f382c280d9 100644 --- a/drivers/staging/rtl8723bs/core/rtw_security.c +++ b/drivers/staging/rtl8723bs/core/rtw_security.c @@ -868,29 +868,21 @@ static signed int aes_cipher(u8 *key, uint hdrlen, num_blocks, payload_index;

u8 pn_vector[6]; - u8 mic_iv[16]; - u8 mic_header1[16]; - u8 mic_header2[16]; - u8 ctr_preload[16]; + u8 mic_iv[16] = {}; + u8 mic_header1[16] = {}; + u8 mic_header2[16] = {}; + u8 ctr_preload[16] = {};

/* Intermediate Buffers */ - u8 chain_buffer[16]; - u8 aes_out[16]; - u8 padded_buffer[16]; + u8 chain_buffer[16] = {}; + u8 aes_out[16] = {}; + u8 padded_buffer[16] = {}; u8 mic[8]; uint frtype = GetFrameType(pframe); uint frsubtype = GetFrameSubType(pframe);

frsubtype = frsubtype>>4;

- memset((void *)mic_iv, 0, 16); - memset((void *)mic_header1, 0, 16); - memset((void *)mic_header2, 0, 16); - memset((void *)ctr_preload, 0, 16); - memset((void *)chain_buffer, 0, 16); - memset((void *)aes_out, 0, 16); - memset((void *)padded_buffer, 0, 16); - if ((hdrlen == WLAN_HDR_A3_LEN) || (hdrlen == WLAN_HDR_A3_QOS_LEN)) a4_exists = 0; else @@ -1080,15 +1072,15 @@ static signed int aes_decipher(u8 *key, uint hdrlen, num_blocks, payload_index; signed int res = _SUCCESS; u8 pn_vector[6]; - u8 mic_iv[16]; - u8 mic_header1[16]; - u8 mic_header2[16]; - u8 ctr_preload[16]; + u8 mic_iv[16] = {}; + u8 mic_header1[16] = {}; + u8 mic_header2[16] = {}; + u8 ctr_preload[16] = {};

/* Intermediate Buffers */ - u8 chain_buffer[16]; - u8 aes_out[16]; - u8 padded_buffer[16]; + u8 chain_buffer[16] = {}; + u8 aes_out[16] = {}; + u8 padded_buffer[16] = {}; u8 mic[8];

uint frtype = GetFrameType(pframe); @@ -1096,14 +1088,6 @@ static signed int aes_decipher(u8 *key, uint hdrlen,

frsubtype = frsubtype>>4;

- memset((void *)mic_iv, 0, 16); - memset((void *)mic_header1, 0, 16); - memset((void *)mic_header2, 0, 16); - memset((void *)ctr_preload, 0, 16); - memset((void *)chain_buffer, 0, 16); - memset((void *)aes_out, 0, 16); - memset((void *)padded_buffer, 0, 16); - /* start to decrypt the payload */

num_blocks = (plen-8) / 16; /* plen including LLC, payload_length and mic) */

--- base-commit: 19272b37aa4f83ca52bdf9c16d5d81bdd1354494 change-id: 20250609-rtl8723bs-fix-clang-arm64-wflt-b4b9652904b5

Best regards,