5.15-stable review patch. If anyone has any objections, please let me know.
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From: Paolo Abeni pabeni@redhat.com
commit 551844f26da2a9f76c0a698baaffa631d1178645 upstream.
Under some corner cases the MPTCP protocol can end-up invoking mptcp_cleanup_rbuf() when no data has been copied, but such helper assumes the opposite condition.
Explicitly drop such assumption and performs the costly call only when strictly needed - before releasing the msk socket lock.
Fixes: fd8976790a6c ("mptcp: be careful on MPTCP-level ack.") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Link: https://patch.msgid.link/20241230-net-mptcp-rbuf-fixes-v1-2-8608af434ceb@ker... Signed-off-by: Jakub Kicinski kuba@kernel.org [ Conflicts in this version, because commit 581302298524 ("mptcp: error out earlier on disconnect") has not been backported to this version, and there was no need to do so. The only conflict was in protocol.c, and easy to resolve: the context was different, but the same addition can still be made at the same spot in mptcp_recvmsg(). ] Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/mptcp/protocol.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-)
--- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -462,13 +462,13 @@ static void mptcp_send_ack(struct mptcp_ mptcp_subflow_send_ack(mptcp_subflow_tcp_sock(subflow)); }
-static void mptcp_subflow_cleanup_rbuf(struct sock *ssk) +static void mptcp_subflow_cleanup_rbuf(struct sock *ssk, int copied) { bool slow;
slow = lock_sock_fast(ssk); if (tcp_can_send_ack(ssk)) - tcp_cleanup_rbuf(ssk, 1); + tcp_cleanup_rbuf(ssk, copied); unlock_sock_fast(ssk, slow); }
@@ -485,7 +485,7 @@ static bool mptcp_subflow_could_cleanup( (ICSK_ACK_PUSHED2 | ICSK_ACK_PUSHED))); }
-static void mptcp_cleanup_rbuf(struct mptcp_sock *msk) +static void mptcp_cleanup_rbuf(struct mptcp_sock *msk, int copied) { int old_space = READ_ONCE(msk->old_wspace); struct mptcp_subflow_context *subflow; @@ -493,14 +493,14 @@ static void mptcp_cleanup_rbuf(struct mp int space = __mptcp_space(sk); bool cleanup, rx_empty;
- cleanup = (space > 0) && (space >= (old_space << 1)); - rx_empty = !__mptcp_rmem(sk); + cleanup = (space > 0) && (space >= (old_space << 1)) && copied; + rx_empty = !__mptcp_rmem(sk) && copied;
mptcp_for_each_subflow(msk, subflow) { struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
if (cleanup || mptcp_subflow_could_cleanup(ssk, rx_empty)) - mptcp_subflow_cleanup_rbuf(ssk); + mptcp_subflow_cleanup_rbuf(ssk, copied); } }
@@ -2098,9 +2098,6 @@ static int mptcp_recvmsg(struct sock *sk
copied += bytes_read;
- /* be sure to advertise window change */ - mptcp_cleanup_rbuf(msk); - if (skb_queue_empty(&msk->receive_queue) && __mptcp_move_skbs(msk)) continue;
@@ -2152,9 +2149,12 @@ static int mptcp_recvmsg(struct sock *sk }
pr_debug("block timeout %ld\n", timeo); + mptcp_cleanup_rbuf(msk, copied); sk_wait_data(sk, &timeo, NULL); }
+ mptcp_cleanup_rbuf(msk, copied); + out_err: if (cmsg_flags && copied >= 0) { if (cmsg_flags & MPTCP_CMSG_TS)