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media: dvb_ca_en50221: sanity check slot number from userspace

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Currently a user can pass in an unsanitized slot number which
will lead to and out of range index into ca->slot_info. Fix this
by checking that the slot number is no more than the allowed
maximum number of slots. Seems that this bug has been in the driver
forever.

Detected by CoverityScan, CID#139381 ("Untrusted pointer read")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Jasmin Jessich <jasmin@anw.at>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Colin Ian King 2017-09-20 18:19:59 -04:00 committed by Mauro Carvalho Chehab
parent 3ee6229f1a
commit a24e6348e5
1 changed files with 3 additions and 0 deletions
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3
drivers/media/dvb-core/dvb_ca_en50221.c
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@ -1473,6 +1473,9 @@ static ssize_t dvb_ca_en50221_io_write(struct file *file,
return -EFAULT;
buf += 2;
count -= 2;
if (slot >= ca->slot_count)
return -EINVAL;
sl = &ca->slot_info[slot];
/* check if the slot is actually running */