Staging: comedi: s626: Possible read buffer overflow fix

If `cmd->chanlist_len' is 0, then we write ppl[-1].

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/staging/comedi/drivers/s626.c b/drivers/staging/comedi/drivers/s626.c
index 6549d116f2e..80d2787d106 100644
--- a/drivers/staging/comedi/drivers/s626.c
+++ b/drivers/staging/comedi/drivers/s626.c
@@ -1707,7 +1707,8 @@ static int s626_ai_load_polllist(uint8_t * ppl, struct comedi_cmd *cmd)
                 else
                         ppl[n] = (CR_CHAN((cmd->chanlist)[n])) | (RANGE_10V);
         }
-        ppl[n - 1] |= EOPL;
+        if (n != 0)
+                ppl[n - 1] |= EOPL;
 
         return n;
 }