raspi/linux
1
0
Fork 1
mirror of https://github.com/raspberrypi/linux.git synced 2025-12-06 01:49:46 +00:00
Code Issues Projects Releases Wiki Activity

comedi: fix divide-by-zero in comedi_buf_munge()

Browse Source 
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>
This commit is contained in:
Deepanshu Kartikey
2025-09-24 15:56:39 +05:30
committed by Greg Kroah-Hartman
parent 98718e80af
commit 87b318ba81
1 changed files with 1 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/comedi/comedi_buf.c
View File

@@ -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;
}