ALSA: cs46xx: fix unit mismatch in DSP code area bounds check

ins->code.offset and code->size are measured in 32-bit words, while
DSP_CODE_BYTE_SIZE is the size of the DSP code area in bytes. The
check ins->code.offset + code->size > DSP_CODE_BYTE_SIZE in
cs46xx_dsp_load_module() therefore allowed up to four times more code
than the code area can hold.

The shadow buffer ins->code.data is allocated with
kmalloc(DSP_CODE_BYTE_SIZE), i.e. it holds DSP_CODE_BYTE_SIZE/4
words. A firmware file with a code segment larger than
DSP_CODE_BYTE_SIZE/4 words (28 KiB) passed the check and caused an
out-of-bounds write in shadow_and_reallocate_code() and an
out-of-bounds read in snd_cs46xx_download().

Compare the sum in words against DSP_CODE_BYTE_SIZE/4 and cast it to
u64 so that the sum cannot wrap for large code->size values.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Denis Arefev <arefev@swemel.ru>
Link: https://patch.msgid.link/20261014102619.16415-1-arefev@swemel.ru
Signed-off-by: Takashi Iwai <tiwai@suse.de>

0 files changed, 0 insertions, 0 deletions