diff options
| author | Eric Dumazet <[email protected]> | 2020-01-22 09:07:35 -0800 |
|---|---|---|
| committer | David S. Miller <[email protected]> | 2020-01-23 11:42:44 +0100 |
| commit | 1efba987c48629c0c64703bb4ea76ca1a3771d17 (patch) | |
| tree | 0bdb2a5ca6a7059cdba16ed9b163b485f431f171 | |
| parent | 971de2e572118c1128bff295341e37b6c8b8f108 (diff) | |
tun: add mutex_unlock() call and napi.skb clearing in tun_get_user()
If both IFF_NAPI_FRAGS mode and XDP are enabled, and the XDP program
consumes the skb, we need to clear the napi.skb (or risk
a use-after-free) and release the mutex (or risk a deadlock)
WARNING: lock held when returning to user space!
5.5.0-rc6-syzkaller #0 Not tainted
------------------------------------------------
syz-executor.0/455 is leaving the kernel with locks still held!
1 lock held by syz-executor.0/455:
#0: ffff888098f6e748 (&tfile->napi_mutex){+.+.}, at: tun_get_user+0x1604/0x3fc0 drivers/net/tun.c:1835
Fixes: 90e33d459407 ("tun: enable napi_gro_frags() for TUN/TAP driver")
Signed-off-by: Eric Dumazet <[email protected]>
Reported-by: syzbot <[email protected]>
Cc: Petar Penkov <[email protected]>
Cc: Willem de Bruijn <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
| -rw-r--r-- | drivers/net/tun.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 683d371e6e82..35e884a8242d 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1936,6 +1936,10 @@ drop: if (ret != XDP_PASS) { rcu_read_unlock(); local_bh_enable(); + if (frags) { + tfile->napi.skb = NULL; + mutex_unlock(&tfile->napi_mutex); + } return total_len; } } |