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 --- 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 d0a480c40231..aa6823fbd1a4 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) {