[PATCH v3] nvme-tcp: Validate the queue state under the queue lock in the address attribute

[Nilay Shroff]

On 10/27/26 6:09 PM, Guixin Liu wrote:
> Reading the "address" sysfs attribute calls kernel_getsockname() on the
> admin queue socket, which can race with the queue teardown during
> connection error recovery: a reader can observe NVME_TCP_Q_LIVE set,
> then block on the queue lock while nvme_tcp_free_queue() releases the
> socket and clears queue->sock without holding the lock.  Once the
> reader acquires the lock it dereferences the NULL socket pointer.
> 
> Commit 76d54bf20cdc ("nvme-tcp: don't access released socket during
> error recovery") had the queue liveness check inside the lock.
> Commit 782373ba2766 ("nvme: tcp: avoid race between queue_lock lock
> and destroy") moved it back out because the lock itself is destroyed
> in nvme_tcp_free_queue(), so a reader arriving late trips
> mutex_destroy().
> 
> Check the queue liveness inside the queue lock, and clear queue->sock
> under the same lock.  The teardown clears NVME_TCP_Q_LIVE under the
> lock well before the socket is released, so a reader either sees the
> bit cleared or a socket that cannot be released while it holds the
> lock.  To also close the lock lifetime race, the queue locks are now
> owned by the controller: they are initialized with the queue array and
> only destroyed when the controller is freed, which cannot happen while
> a sysfs attribute read is still in progress.  The queue count is
> computed by the NVME_TCP_OPT_NR_QUEUES() macro from the original
> connect options for both initialization and destruction, as reconnects
> may shrink ctrl->queue_count.
> 
> Fixes: 782373ba2766 ("nvme: tcp: avoid race between queue_lock lock and destroy")
> Cc:stable at vger.kernel.org
> Signed-off-by: Guixin Liu<kanie at linux.alibaba.com>

Looks good to me:
Reviewed-by: Nilay Shroff <nilay at linux.ibm.com>