[PATCH AUTOSEL 5.17 02/22] ASoC: cs35l41: Fix a shift-out-of-bounds warning found by UBSAN

Sasha Levin
2022-04-26T19:03:29Z

From: Hui Wang <hui.wang@canonical.com>

[ Upstream commit 0b3d5d2e358ca6772fc3662fca27acb12a682fbf ]

We enabled UBSAN in the ubuntu kernel, and the cs35l41 driver triggers
a warning calltrace like below:

cs35l41-hda i2c-CSC3551:00-cs35l41-hda.0: bitoffset= 8, word_offset=23, bit_sum mod 32=0, otp_map[i].size = 24
cs35l41-hda i2c-CSC3551:00-cs35l41-hda.0: bitoffset= 0, word_offset=24, bit_sum mod 32=24, otp_map[i].size = 0
================================================================================
UBSAN: shift-out-of-bounds in linux-kernel-src/sound/soc/codecs/cs35l41-lib.c:836:8
shift exponent 64 is too large for 64-bit type 'long unsigned int'
CPU: 10 PID: 595 Comm: systemd-udevd Not tainted 5.15.0-23-generic #23
Hardware name: LENOVO \x02MFG_IN_GO/\x02MFG_IN_GO, BIOS N3GET19W (1.00 ) 03/11/2022
Call Trace:
<TASK>
show_stack+0x52/0x58
dump_stack_lvl+0x4a/0x5f
dump_stack+0x10/0x12
ubsan_epilogue+0x9/0x45
__ubsan_handle_shift_out_of_bounds.cold+0x61/0xef
? regmap_unlock_mutex+0xe/0x10
cs35l41_otp_unpack.cold+0x1c6/0x2b2 [snd_soc_cs35l41_lib]
cs35l41_hda_probe+0x24f/0x33a [snd_hda_scodec_cs35l41]
cs35l41_hda_i2c_probe+0x65/0x90 [snd_hda_scodec_cs35l41_i2c]

When both bitoffset and otp_map[i].size are 0, the line 836 will
result in GENMASK(-1, 0), this triggers the shift-out-of-bounds
calltrace.

Here add a checking, if both bitoffset and otp_map[i].size are 0,
do not run GENMASK() and directly set otp_val to 0, this will not
bring any function change on the driver but could avoid the calltrace.

Signed-off-by: Hui Wang <hui.wang@canonical.com>
Link: https://lore.kernel.org/r/20220324081839.62009-2-hui.wang@canonical.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
sound/soc/codecs/cs35l41-lib.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/sound/soc/codecs/cs35l41-lib.c b/sound/soc/codecs/cs35l41-lib.c
index e5a56bcbb223..281a710a4123 100644
--- a/sound/soc/codecs/cs35l41-lib.c
+++ b/sound/soc/codecs/cs35l41-lib.c
@@ -831,12 +831,14 @@ int cs35l41_otp_unpack(struct device *dev, struct regmap *regmap)
GENMASK(bit_offset + otp_map[i].size - 33, 0)) <<
(32 - bit_offset);
bit_offset += otp_map[i].size - 32;
- } else {
+ } else if (bit_offset + otp_map[i].size - 1 >= 0) {
otp_val = (otp_mem[word_offset] &
GENMASK(bit_offset + otp_map[i].size - 1, bit_offset)
) >> bit_offset;
bit_offset += otp_map[i].size;
- }
+ } else /* both bit_offset and otp_map[i].size are 0 */
+ otp_val = 0;
+
bit_sum += otp_map[i].size;

if (bit_offset == 32) {
--
2.35.1