path: root/net/rxrpc/recvmsg.c
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authorDavid Howells <dhowells@redhat.com>2019-08-09 15:20:41 +0100
committerDavid Howells <dhowells@redhat.com>2019-08-09 15:21:19 +0100
commit730c5fd42c1e3652a065448fd235cb9fafb2bd10 (patch)
tree60585660be245d94c51a42f4bfa25e488299aca0 /net/rxrpc/recvmsg.c
parentnet: tundra: tsi108: use spin_lock_irqsave instead of spin_lock_irq in IRQ context (diff)
rxrpc: Fix local endpoint refcounting
The object lifetime management on the rxrpc_local struct is broken in that the rxrpc_local_processor() function is expected to clean up and remove an object - but it may get requeued by packets coming in on the backing UDP socket once it starts running. This may result in the assertion in rxrpc_local_rcu() firing because the memory has been scheduled for RCU destruction whilst still queued: rxrpc: Assertion failed ------------[ cut here ]------------ kernel BUG at net/rxrpc/local_object.c:468! Note that if the processor comes around before the RCU free function, it will just do nothing because ->dead is true. Fix this by adding a separate refcount to count active users of the endpoint that causes the endpoint to be destroyed when it reaches 0. The original refcount can then be used to refcount objects through the work processor and cause the memory to be rcu freed when that reaches 0. Fixes: 4f95dd78a77e ("rxrpc: Rework local endpoint management") Reported-by: syzbot+1e0edc4b8b7494c28450@syzkaller.appspotmail.com Signed-off-by: David Howells <dhowells@redhat.com>
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