diff options
| author | Pavel Skripkin <paskripkin@gmail.com> | 2021-08-13 18:14:33 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-08-16 11:08:05 +0100 |
| commit | 19d1532a187669ce86d5a2696eb7275310070793 (patch) | |
| tree | 6cfe659134260876b5e31eb3e4cc43e14631aa7c /drivers | |
| parent | 5f773519639041faed4132f5943d7895f9078a4c (diff) | |
net: 6pack: fix slab-out-of-bounds in decode_data
Syzbot reported slab-out-of bounds write in decode_data().
The problem was in missing validation checks.
Syzbot's reproducer generated malicious input, which caused
decode_data() to be called a lot in sixpack_decode(). Since
rx_count_cooked is only 400 bytes and noone reported before,
that 400 bytes is not enough, let's just check if input is malicious
and complain about buffer overrun.
Fail log:
==================================================================
BUG: KASAN: slab-out-of-bounds in drivers/net/hamradio/6pack.c:843
Write of size 1 at addr ffff888087c5544e by task kworker/u4:0/7
CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 5.6.0-rc3-syzkaller #0
...
Workqueue: events_unbound flush_to_ldisc
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x197/0x210 lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
__kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506
kasan_report+0x12/0x20 mm/kasan/common.c:641
__asan_report_store1_noabort+0x17/0x20 mm/kasan/generic_report.c:137
decode_data.part.0+0x23b/0x270 drivers/net/hamradio/6pack.c:843
decode_data drivers/net/hamradio/6pack.c:965 [inline]
sixpack_decode drivers/net/hamradio/6pack.c:968 [inline]
Reported-and-tested-by: syzbot+fc8cd9a673d4577fb2e4@syzkaller.appspotmail.com
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/net/hamradio/6pack.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c index fcf3af76b6d7..8fe8887d506a 100644 --- a/drivers/net/hamradio/6pack.c +++ b/drivers/net/hamradio/6pack.c @@ -827,6 +827,12 @@ static void decode_data(struct sixpack *sp, unsigned char inbyte) return; } + if (sp->rx_count_cooked + 2 >= sizeof(sp->cooked_buf)) { + pr_err("6pack: cooked buffer overrun, data loss\n"); + sp->rx_count = 0; + return; + } + buf = sp->raw_buf; sp->cooked_buf[sp->rx_count_cooked++] = buf[0] | ((buf[1] << 2) & 0xc0); |