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authorEric Dumazet <edumazet@google.com>2023-08-03 19:30:21 +0300
committerJakub Kicinski <kuba@kernel.org>2023-08-05 04:27:58 +0300
commita47e598fbd8617967e49d85c49c22f9fc642704c (patch)
tree7d9d662e64eb37268b7197729e3cafac5d59bf81 /net/dccp
parentfc2ea6ab0a73b58328c61237017e28ba49b3a21e (diff)
downloadlinux-a47e598fbd8617967e49d85c49c22f9fc642704c.tar.xz
dccp: fix data-race around dp->dccps_mss_cache
dccp_sendmsg() reads dp->dccps_mss_cache before locking the socket. Same thing in do_dccp_getsockopt(). Add READ_ONCE()/WRITE_ONCE() annotations, and change dccp_sendmsg() to check again dccps_mss_cache after socket is locked. Fixes: 7c657876b63c ("[DCCP]: Initial implementation") Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20230803163021.2958262-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/dccp')
-rw-r--r--net/dccp/output.c2
-rw-r--r--net/dccp/proto.c10
2 files changed, 9 insertions, 3 deletions
diff --git a/net/dccp/output.c b/net/dccp/output.c
index b8a24734385e..fd2eb148d24d 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -187,7 +187,7 @@ unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
/* And store cached results */
icsk->icsk_pmtu_cookie = pmtu;
- dp->dccps_mss_cache = cur_mps;
+ WRITE_ONCE(dp->dccps_mss_cache, cur_mps);
return cur_mps;
}
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index f331e5977a84..4e3266e4d7c3 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -630,7 +630,7 @@ static int do_dccp_getsockopt(struct sock *sk, int level, int optname,
return dccp_getsockopt_service(sk, len,
(__be32 __user *)optval, optlen);
case DCCP_SOCKOPT_GET_CUR_MPS:
- val = dp->dccps_mss_cache;
+ val = READ_ONCE(dp->dccps_mss_cache);
break;
case DCCP_SOCKOPT_AVAILABLE_CCIDS:
return ccid_getsockopt_builtin_ccids(sk, len, optval, optlen);
@@ -739,7 +739,7 @@ int dccp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
trace_dccp_probe(sk, len);
- if (len > dp->dccps_mss_cache)
+ if (len > READ_ONCE(dp->dccps_mss_cache))
return -EMSGSIZE;
lock_sock(sk);
@@ -772,6 +772,12 @@ int dccp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
goto out_discard;
}
+ /* We need to check dccps_mss_cache after socket is locked. */
+ if (len > dp->dccps_mss_cache) {
+ rc = -EMSGSIZE;
+ goto out_discard;
+ }
+
skb_reserve(skb, sk->sk_prot->max_header);
rc = memcpy_from_msg(skb_put(skb, len), msg, len);
if (rc != 0)