Input: rmi_smbus - fix out-of-bounds read in rmi_smb_write_block()

When chunking writes into SMBus blocks in rmi_smb_write_block(), the
loop calculates block_len using the original total length (len) instead
of the remaining length (cur_len).

If len is greater than 32 bytes (SMB_MAX_COUNT), block_len remains 32
for every iteration, even on the final partial chunk where fewer than 32
bytes remain. This causes smb_block_write() to read 32 bytes from the
advanced data buffer pointer, reading past the end of the input buffer.

Fix this by calculating block_len using cur_len and advancing the buffer
and address pointers by block_len.

Fixes: 82264d0cf7ae ("Input: synaptics-rmi4 - add SMBus support")
Cc: stable@vger.kernel.org
Reported-by: sashiko-bot@kernel.org
Assisted-by: LLM
Link: https://patch.msgid.link/anLFSMKSoKyyZ272@google.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

0 files changed, 0 insertions, 0 deletions