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| author | Deepanshu Kartikey <kartikey406@gmail.com> | 2025-09-24 15:56:39 +0530 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-10-29 14:00:00 +0100 |
| commit | 4ffea48c69cb2b96a281cb7e5e42d706996631db (patch) | |
| tree | 2cb86330164fe55212cca70436f4ee8f44ef8d1e | |
| parent | 9d053f98561316e903a3bc269022afc6fbb2b842 (diff) | |
| download | linux-4ffea48c69cb2b96a281cb7e5e42d706996631db.tar.gz linux-4ffea48c69cb2b96a281cb7e5e42d706996631db.tar.bz2 linux-4ffea48c69cb2b96a281cb7e5e42d706996631db.zip | |
comedi: fix divide-by-zero in comedi_buf_munge()
commit 87b318ba81dda2ee7b603f4f6c55e78ec3e95974 upstream.
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/staging/comedi/comedi_buf.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/staging/comedi/comedi_buf.c b/drivers/staging/comedi/comedi_buf.c index 3ef3ddabf139..3df045b25cb3 100644 --- a/drivers/staging/comedi/comedi_buf.c +++ b/drivers/staging/comedi/comedi_buf.c @@ -369,7 +369,7 @@ 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; count = num_bytes; } else { |