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b=feXwoZrwG59Pa7h4jjC11zjzA53EvBCTat4ec6sIALr0ZGwPmteygrtLhu4VaI2xov Wc58RtBU1709NVT0OnYiQo4WFneG+IXLjhvvxSmD2cdP0tER76jlBnBfaMgxiVOqiaxs ZKd0qJFsWfesM1L10zIurUKb0FD9rkf7D2F1Uou8dr+m3vzzcSeXNjTCwMikyypf5FCz rCD2S88MgnKeHBxUCbFNXjA8QUZblXZT9a4r9jMhW6HuWofY60t+3sCUhAlQLEQR7+Rh rQ+2mUThslt/hamz0KBWVRp3+2ztlFbofb0xiYlc8VUZQYwC3PQ+sS2I7pECpUhn+9xt x6TQ== X-Forwarded-Encrypted: i=1; AKwUvBz0sx+ar7M++sFus4b20TRPSPiN6aJ8q6dVEuhf6wkQdD1vwW7o/Mvc6BARYnv9suB+XlCUrYN6CryH@vger.kernel.org X-Gm-Message-State: AFq9FYJG+W+DeXEdqBo/kLH5ao6L7CKMB9UGtixwiX0d9YltleeHnQxE K/+tF4T6iZ+MMCY1k/MhxRd7Fehrd8te4gHA2WHI5hCJn9j9Gn3xuj+cRc1AzvH0Kg7imdMLt5i 6U8IHaSSYDWMBjqSYhJWFcQ== X-Received: from pjps6.prod.google.com ([2002:a17:90a:a106:b0:3ad:c8d8:70c3]) (user=jthoughton job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:2688:b0:3a8:cb54:e135 with SMTP id 98e67ed59e1d1-3adea899125mr6172313a91.19.1793051568668; Mon, 26 Oct 2026 14:52:48 -0700 (PDT) Date: Mon, 26 Oct 2026 21:52:17 +0000 In-Reply-To: <20261026215226.3713941-1-jthoughton@google.com> X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list Mime-Version: 1.0 References: <20261026215226.3713941-1-jthoughton@google.com> X-Mailer: git-send-email 2.56.0.307.g5fe7bd680c-goog Message-ID: <20261026215226.3713941-2-jthoughton@google.com> Subject: [RFC PATCH 01/10] scsi: bsg: Don't copy sense data to user memory when canceled From: James Houghton To: Andrew Morton , Alexander Viro Cc: Thomas Gleixner , Peter Zijlstra , Kees Cook , Arnd Bergmann , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Sean Christopherson , Paolo Bonzini , Jim Mattson , Jens Axboe , Pavel Begunkov , "James E.J. Bottomley" , "Martin K. Petersen" , David Sterba , Chris Mason , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Josh Poimboeuf , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, kvm@vger.kernel.org, io-uring@vger.kernel.org, linux-scsi@vger.kernel.org, linux-btrfs@vger.kernel.org, bpf@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, James Houghton Content-Type: text/plain; charset="UTF-8" scsi_bsg_uring_task_cb() copies the sense data to the submitter's response_addr with copy_to_user(). It runs as io_uring task work, but io_uring may also run it with tw.cancel set from other contexts when the submitting task can't run it: from a kworker when the submitting task has exited (io_tctx_fallback_work()), or from io_cancel_local_task_work() when a DEFER_TASKRUN ring is torn down. In a kworker, current->mm is NULL, and the copy does not reliably fail: the user half of the address space belongs to whatever mm happens to be lazily loaded, if any, so up to max_response_len bytes of sense data may be written into an unrelated process. Don't copy the sense data when the task work is canceled, and complete the command with -ECANCELED. Fixes: 7b6d3255e7f8 ("scsi: bsg: add io_uring passthrough handler") Signed-off-by: James Houghton --- drivers/scsi/scsi_bsg.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/scsi_bsg.c b/drivers/scsi/scsi_bsg.c index 5eec248a77a6..3755e33fcdd2 100644 --- a/drivers/scsi/scsi_bsg.c +++ b/drivers/scsi/scsi_bsg.c @@ -43,9 +43,17 @@ static void scsi_bsg_uring_task_cb(struct io_tw_req tw_req, io_tw_token_t tw) if (pdu->bio) blk_rq_unmap_user(pdu->bio); + /* + * If the request is being canceled, e.g. because the submitting task + * has exited, this may run from a kworker or in a different task, so + * don't copy the sense data to the submitter's address. + */ + if (unlikely(tw.cancel)) + ret = -ECANCELED; + if (scsi_status_is_check_condition(scmd->result)) { driver_status = DRIVER_SENSE; - if (pdu->response_addr) + if (pdu->response_addr && !tw.cancel) sense_len_wr = min_t(unsigned int, pdu->max_response_len, scmd->sense_len); } -- 2.56.0.307.g5fe7bd680c-goog