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| author | Eric Dumazet <edumazet@google.com> | 2020-01-22 20:07:35 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-01-29 18:43:17 +0300 |
| commit | 8f50a05dd6fe2372ac0d5c67645e4e480254ce30 (patch) | |
| tree | f294efb4cbcf3ee2c4da4492978d63df039c7cec | |
| parent | 9bbde0825846002c6931f41fbbd71eeb848ca0e1 (diff) | |
| download | linux-8f50a05dd6fe2372ac0d5c67645e4e480254ce30.tar.xz | |
tun: add mutex_unlock() call and napi.skb clearing in tun_get_user()
[ Upstream commit 1efba987c48629c0c64703bb4ea76ca1a3771d17 ]
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 <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Petar Penkov <ppenkov@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 bbd92221c6ca..09c444d3b496 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1900,6 +1900,10 @@ 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; } } |