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b=KMOHjEPAU8vBzBHEK+mAbgwG/jp8eM9bXNbNl2QkGwbx2oUSip7VXVU24GiavviuM7 Rq4dNCYv8vtXe+n3xwitNnz/y9RDZKMjpmTwTSKUfg2h6/Ka8ZXh9gnN99m96nmu8gIZ EddMV9EykVSONAM1MypRecJf9neBuEBxTMV6652qb4FW3SPvtrEB7CIktRUaVbiyGn9N rb5hTwdoFnl5DfquDDNn6twbC2S0FCe6NXQ47LcylIvqNvZ4pzcc1vFkzALpCSwyw0n6 0yOHjzZ6Pe6B3NWDhOXInmMH9n2RhkWZOV1aIHgAbd6Capf6qSe1bDjeoj76H0Tsykta oKRw== X-Forwarded-Encrypted: i=1; AKwUvByOqmCVC+ln4/owaRsD9swQ2h79ocwtpDIKYpXMZIhLhzAzC+uvA7pbKHDx+wwWKBX/W3kYQZa19EQiTGo=@vger.kernel.org X-Gm-Message-State: AFq9FYJeR2kdMxIsThZ3Gg9t5zEyQ3mb2FcLvpP/Bd9z6iHhxIaM4cpQ dETfa6hx1RUrLxTk2xKMdrrvDXBD/Rj4QZcCUNc1DLXCt9r2i1Vp2koPC72w2AaPnPRnIiRU+eU O4RVktbA0q9cchK39ITL2Bw== 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-kernel@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