diff options
| author | Deepanshu Kartikey <kartikey406@gmail.com> | 2025-09-24 15:56:39 +0530 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-10-22 08:03:52 +0200 |
| commit | 87b318ba81dda2ee7b603f4f6c55e78ec3e95974 (patch) | |
| tree | df7cfd03c0f2d7cd1e19d2edff5c02493cc4d774 | |
| parent | 98718e80af0bb1cd80f4bfe565dd60c57debad51 (diff) | |
comedi: fix divide-by-zero in comedi_buf_munge()
The comedi_buf_munge() function performs a modulo operation
`async->munge_chan %= async->cmd.chanlist_len` without first
checking if chanlist_len is zero. If a user program submits a command with
chanlist_len set to zero, this causes a divide-by-zero error when the device
processes data in the interrupt handler path.
Add a check for zero chanlist_len at the beginning of the
function, similar to the existing checks for !map and
CMDF_RAWDATA flag. When chanlist_len is zero, update
munge_count and return early, indicating the data was
handled without munging.
This prevents potential kernel panics from malformed user commands.
Reported-by: syzbot+f6c3c066162d2c43a66c@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=f6c3c066162d2c43a66c
Cc: stable@vger.kernel.org
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://patch.msgid.link/20250924102639.1256191-1-kartikey406@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/comedi/comedi_buf.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/comedi/comedi_buf.c b/drivers/comedi/comedi_buf.c index 002c0e76baff..c7c262a2d8ca 100644 --- a/drivers/comedi/comedi_buf.c +++ b/drivers/comedi/comedi_buf.c @@ -317,7 +317,7 @@ static unsigned int comedi_buf_munge(struct comedi_subdevice *s, unsigned int count = 0; const unsigned int num_sample_bytes = comedi_bytes_per_sample(s); - if (!s->munge || (async->cmd.flags & CMDF_RAWDATA)) { + if (!s->munge || (async->cmd.flags & CMDF_RAWDATA) || async->cmd.chanlist_len == 0) { async->munge_count += num_bytes; return num_bytes; } |