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[ Upstream commit2c28769a51] If rxrpc_recvmsg() fails because MSG_DONTWAIT was specified but the call at the front of the recvmsg queue already has its mutex locked, it requeues the call - whether or not the call is already queued. The call may be on the queue because MSG_PEEK was also passed and so the call was not dequeued or because the I/O thread requeued it. The unconditional requeue may then corrupt the recvmsg queue, leading to things like UAFs or refcount underruns. Fix this by only requeuing the call if it isn't already on the queue - and moving it to the front if it is already queued. If we don't queue it, we have to put the ref we obtained by dequeuing it. Also, MSG_PEEK doesn't dequeue the call so shouldn't call rxrpc_notify_socket() for the call if we didn't use up all the data on the queue, so fix that also. Fixes:540b1c48c3("rxrpc: Fix deadlock between call creation and sendmsg/recvmsg") Reported-by: Faith <faith@zellic.io> Reported-by: Pumpkin Chang <pumpkin@devco.re> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Marc Dionne <marc.dionne@auristor.com> cc: Nir Ohfeld <niro@wiz.io> cc: Willy Tarreau <w@1wt.eu> cc: Simon Horman <horms@kernel.org> cc: linux-afs@lists.infradead.org cc: stable@kernel.org Link: https://patch.msgid.link/95163.1768428203@warthog.procyon.org.uk Signed-off-by: Jakub Kicinski <kuba@kernel.org> [Use spin_unlock instead of spin_unlock_irq to maintain context consistency.] Signed-off-by: Robert Garcia <rob_garcia@163.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>