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authorPaolo Abeni <pabeni@redhat.com>2021-06-09 11:49:01 +0200
committerDavid S. Miller <davem@davemloft.net>2021-06-09 14:08:41 -0700
commita8b897c7bcd47f4147d066e22cc01d1026d7640e (patch)
treef8423df1a5a624483c4cbd8c53fc7e0c05708fab /net
parentdcd01eeac14486b56a790f5cce9b823440ba5b34 (diff)
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udp: fix race between close() and udp_abort()
Kaustubh reported and diagnosed a panic in udp_lib_lookup(). The root cause is udp_abort() racing with close(). Both racing functions acquire the socket lock, but udp{v6}_destroy_sock() release it before performing destructive actions. We can't easily extend the socket lock scope to avoid the race, instead use the SOCK_DEAD flag to prevent udp_abort from doing any action when the critical race happens. Diagnosed-and-tested-by: Kaustubh Pandey <kapandey@codeaurora.org> Fixes: 5d77dca82839 ("net: diag: support SOCK_DESTROY for UDP sockets") Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/udp.c10
-rw-r--r--net/ipv6/udp.c3
2 files changed, 13 insertions, 0 deletions
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 15f5504adf5b..1307ad0d3b9e 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2607,6 +2607,9 @@ void udp_destroy_sock(struct sock *sk)
{
struct udp_sock *up = udp_sk(sk);
bool slow = lock_sock_fast(sk);
+
+ /* protects from races with udp_abort() */
+ sock_set_flag(sk, SOCK_DEAD);
udp_flush_pending_frames(sk);
unlock_sock_fast(sk, slow);
if (static_branch_unlikely(&udp_encap_needed_key)) {
@@ -2857,10 +2860,17 @@ int udp_abort(struct sock *sk, int err)
{
lock_sock(sk);
+ /* udp{v6}_destroy_sock() sets it under the sk lock, avoid racing
+ * with close()
+ */
+ if (sock_flag(sk, SOCK_DEAD))
+ goto out;
+
sk->sk_err = err;
sk->sk_error_report(sk);
__udp_disconnect(sk, 0);
+out:
release_sock(sk);
return 0;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 199b080d418a..3fcd86f4dfdc 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1598,6 +1598,9 @@ void udpv6_destroy_sock(struct sock *sk)
{
struct udp_sock *up = udp_sk(sk);
lock_sock(sk);
+
+ /* protects from races with udp_abort() */
+ sock_set_flag(sk, SOCK_DEAD);
udp_v6_flush_pending_frames(sk);
release_sock(sk);