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| author | Florian Westphal <fw@strlen.de> | 2021-12-14 15:16:02 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-12-22 09:30:54 +0100 |
| commit | 451f1eded7f56e93aaf52eb547ba97742d9c0e97 (patch) | |
| tree | b177433968a2b5f2098d97ef685ac9b9a20eb72a /net | |
| parent | 222cebd995cdf11fe0d502749560f65e64990e55 (diff) | |
| download | linux-451f1eded7f56e93aaf52eb547ba97742d9c0e97.tar.gz linux-451f1eded7f56e93aaf52eb547ba97742d9c0e97.tar.bz2 linux-451f1eded7f56e93aaf52eb547ba97742d9c0e97.zip | |
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>
Diffstat (limited to 'net')
| -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 3ca8b359e399..8123c79e2791 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2149,7 +2149,7 @@ 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 */ @@ -2174,6 +2174,8 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err, MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK); } +out: + newsk->sk_kern_sock = kern; return newsk; } |