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authorEric Dumazet <edumazet@google.com>2017-08-14 17:44:43 -0700
committerDavid S. Miller <davem@davemloft.net>2017-08-14 22:31:27 -0700
commitd624d276d1ddacbcb12ad96832ce0c7b82cd25db (patch)
treeb78aa1f2060bf2aa70b13af5d58a7bca994af306
parent7749d4ff88d31b0be17c8683143135adaaadc6a7 (diff)
downloadlinux-d624d276d1ddacbcb12ad96832ce0c7b82cd25db.tar.bz2
tcp: fix possible deadlock in TCP stack vs BPF filter
Filtering the ACK packet was not put at the right place. At this place, we already allocated a child and put it into accept queue. We absolutely need to call tcp_child_process() to release its spinlock, or we will deadlock at accept() or close() time. Found by syzkaller team (Thanks a lot !) Fixes: 8fac365f63c8 ("tcp: Add a tcp_filter hook before handle ack packet") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: Chenbo Feng <fengc@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/tcp_ipv4.c4
-rw-r--r--net/ipv6/tcp_ipv6.c4
2 files changed, 4 insertions, 4 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index a20e7f03d5f7..e9252c7df809 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1722,6 +1722,8 @@ process:
*/
sock_hold(sk);
refcounted = true;
+ if (tcp_filter(sk, skb))
+ goto discard_and_relse;
nsk = tcp_check_req(sk, skb, req, false);
if (!nsk) {
reqsk_put(req);
@@ -1729,8 +1731,6 @@ process:
}
if (nsk == sk) {
reqsk_put(req);
- } else if (tcp_filter(sk, skb)) {
- goto discard_and_relse;
} else if (tcp_child_process(sk, nsk, skb)) {
tcp_v4_send_reset(nsk, skb);
goto discard_and_relse;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 2521690d62d6..206210125fd7 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1456,6 +1456,8 @@ process:
}
sock_hold(sk);
refcounted = true;
+ if (tcp_filter(sk, skb))
+ goto discard_and_relse;
nsk = tcp_check_req(sk, skb, req, false);
if (!nsk) {
reqsk_put(req);
@@ -1464,8 +1466,6 @@ process:
if (nsk == sk) {
reqsk_put(req);
tcp_v6_restore_cb(skb);
- } else if (tcp_filter(sk, skb)) {
- goto discard_and_relse;
} else if (tcp_child_process(sk, nsk, skb)) {
tcp_v6_send_reset(nsk, skb);
goto discard_and_relse;