[PATCH v2] nvme-tcp: Validate the queue state under the queue lock in the address attribute

[Guixin Liu]

在 2026/10/27 19:12, Nilay Shroff 写道:
> On 10/27/26 1:07 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 opts-derived queue
>> count is used 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>
>> ---
>>   drivers/nvme/host/tcp.c | 46 +++++++++++++++++++++++++++++------------
>>   1 file changed, 33 insertions(+), 13 deletions(-)
>>
> [...]
>> @@ -2627,6 +2632,10 @@ static void nvme_tcp_stop_ctrl(struct nvme_ctrl *ctrl)
>>   static void nvme_tcp_free_ctrl(struct nvme_ctrl *nctrl)
>>   {
>>       struct nvme_tcp_ctrl *ctrl = to_tcp_ctrl(nctrl);
>> +    /* the same count used to size and initialize the queue array */
>> +    unsigned int nr_queues = nctrl->opts->nr_io_queues +
>> +        nctrl->opts->nr_write_queues + nctrl->opts->nr_poll_queues + 1;
>
> This looks good. However, since the same expression is used to calculate
> nr_queues during both controller allocation and freeing, would it make
> sense to define a macro for it and reuse it in both places?
Sure, changed in v3.

Best Regards,
Guixin Liu
>
> Thanks,
> --Nilay