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| author | Florian Westphal <fw@strlen.de> | 2021-12-15 02:16:02 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-12-22 11:32:43 +0300 |
| commit | c26ac0ea3a91c210cf90452e625dc441adf3e549 (patch) | |
| tree | 288f4a489b6201f8b53ea18aff32bb9d33ed51d2 | |
| parent | 3de0c86d42f841d1d64f316cd949e65c566f0734 (diff) | |
| download | linux-c26ac0ea3a91c210cf90452e625dc441adf3e549.tar.xz | |
mptcp: clear 'kern' flag from fallback sockets
[ Upstream commit d6692b3b97bdc165d150f4c1505751a323a80717 ]
The mptcp ULP extension relies on sk->sk_sock_kern being set correctly:
It prevents setsockopt(fd, IPPROTO_TCP, TCP_ULP, "mptcp", 6); from
working for plain tcp sockets (any userspace-exposed socket).
But in case of fallback, accept() can return a plain tcp sk.
In such case, sk is still tagged as 'kernel' and setsockopt will work.
This will crash the kernel, The subflow extension has a NULL ctx->conn
mptcp socket:
BUG: KASAN: null-ptr-deref in subflow_data_ready+0x181/0x2b0
Call Trace:
tcp_data_ready+0xf8/0x370
[..]
Fixes: cf7da0d66cc1 ("mptcp: Create SUBFLOW socket for incoming connections")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | net/mptcp/protocol.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 421fa62ce5cd..fdff811c9a0d 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2901,7 +2901,7 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err, */ if (WARN_ON_ONCE(!new_mptcp_sock)) { tcp_sk(newsk)->is_mptcp = 0; - return newsk; + goto out; } /* acquire the 2nd reference for the owning socket */ @@ -2913,6 +2913,8 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err, MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK); } +out: + newsk->sk_kern_sock = kern; return newsk; } |