From: Rahul Chandelkar scsi_bsg_uring_cmd() reads bsg_uring_cmd fields from the shared mmap'd SQE via io_uring_sqe128_cmd(). On the inline path the SQE is still user-writable, so request_len can change between the bounds check and copy_from_user(), overflowing scmd->cmnd. Snapshot request/request_len and the transfer fields used for buffer mapping with READ_ONCE before validation and reuse. Pass the stable map arguments into scsi_bsg_map_user_buffer() so it does not re-read the SQE. Fixes: 7b6d3255e7f8 ("scsi: bsg: add io_uring passthrough handler") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20260527105931.3950913-1-rc@rexion.ai Signed-off-by: Rahul Chandelkar Co-developed-by: Yang Xiuwei Signed-off-by: Yang Xiuwei --- drivers/scsi/scsi_bsg.c | 40 ++++++++++++++++++++++++++-------------- 1 file changed, 26 insertions(+), 14 deletions(-) diff --git a/drivers/scsi/scsi_bsg.c b/drivers/scsi/scsi_bsg.c index e80dec53174e..c57ce01379de 100644 --- a/drivers/scsi/scsi_bsg.c +++ b/drivers/scsi/scsi_bsg.c @@ -76,12 +76,10 @@ static enum rq_end_io_ret scsi_bsg_uring_cmd_done(struct request *req, static int scsi_bsg_map_user_buffer(struct request *req, struct io_uring_cmd *ioucmd, - unsigned int issue_flags, gfp_t gfp_mask) + unsigned int issue_flags, gfp_t gfp_mask, + bool is_write, u64 buf_addr, + unsigned long buf_len) { - const struct bsg_uring_cmd *cmd = io_uring_sqe128_cmd(ioucmd->sqe, struct bsg_uring_cmd); - bool is_write = cmd->dout_xfer_len > 0; - u64 buf_addr = is_write ? cmd->dout_xferp : cmd->din_xferp; - unsigned long buf_len = is_write ? cmd->dout_xfer_len : cmd->din_xfer_len; struct iov_iter iter; int ret; @@ -104,21 +102,29 @@ static int scsi_bsg_uring_cmd(struct request_queue *q, struct io_uring_cmd *iouc unsigned int issue_flags, bool open_for_write) { struct scsi_bsg_uring_cmd_pdu *pdu = scsi_bsg_uring_cmd_pdu(ioucmd); - const struct bsg_uring_cmd *cmd = io_uring_sqe128_cmd(ioucmd->sqe, struct bsg_uring_cmd); + const struct bsg_uring_cmd *cmd = + io_uring_sqe128_cmd(ioucmd->sqe, struct bsg_uring_cmd); struct scsi_cmnd *scmd; struct request *req; blk_mq_req_flags_t blk_flags = 0; gfp_t gfp_mask = GFP_KERNEL; + /* Snapshot SQE fields used for validation and buffer mapping. */ + u64 request = READ_ONCE(cmd->request); + u32 request_len = READ_ONCE(cmd->request_len); + u64 dout_xferp = READ_ONCE(cmd->dout_xferp); + u32 dout_xfer_len = READ_ONCE(cmd->dout_xfer_len); + u64 din_xferp = READ_ONCE(cmd->din_xferp); + u32 din_xfer_len = READ_ONCE(cmd->din_xfer_len); int ret; if (cmd->protocol != BSG_PROTOCOL_SCSI || cmd->subprotocol != BSG_SUB_PROTOCOL_SCSI_CMD) return -EINVAL; - if (!cmd->request || cmd->request_len == 0) + if (!request || request_len == 0) return -EINVAL; - if (cmd->dout_xfer_len && cmd->din_xfer_len) { + if (dout_xfer_len && din_xfer_len) { pr_warn_once("BIDI support in bsg has been removed.\n"); return -EOPNOTSUPP; } @@ -131,20 +137,20 @@ static int scsi_bsg_uring_cmd(struct request_queue *q, struct io_uring_cmd *iouc gfp_mask = GFP_NOWAIT; } - req = scsi_alloc_request(q, cmd->dout_xfer_len ? + req = scsi_alloc_request(q, dout_xfer_len ? REQ_OP_DRV_OUT : REQ_OP_DRV_IN, blk_flags); if (IS_ERR(req)) return PTR_ERR(req); scmd = blk_mq_rq_to_pdu(req); - if (cmd->request_len > sizeof(scmd->cmnd)) { + if (request_len > sizeof(scmd->cmnd)) { ret = -EINVAL; goto out_free_req; } - scmd->cmd_len = cmd->request_len; + scmd->cmd_len = request_len; scmd->allowed = SG_DEFAULT_RETRIES; - if (copy_from_user(scmd->cmnd, uptr64(cmd->request), cmd->request_len)) { + if (copy_from_user(scmd->cmnd, uptr64(request), request_len)) { ret = -EFAULT; goto out_free_req; } @@ -158,8 +164,14 @@ static int scsi_bsg_uring_cmd(struct request_queue *q, struct io_uring_cmd *iouc scmd->sense_len = cmd->max_response_len ? min(cmd->max_response_len, SCSI_SENSE_BUFFERSIZE) : SCSI_SENSE_BUFFERSIZE; - if (cmd->dout_xfer_len || cmd->din_xfer_len) { - ret = scsi_bsg_map_user_buffer(req, ioucmd, issue_flags, gfp_mask); + if (dout_xfer_len || din_xfer_len) { + bool is_write = dout_xfer_len > 0; + u64 buf_addr = is_write ? dout_xferp : din_xferp; + unsigned long buf_len = is_write ? dout_xfer_len : din_xfer_len; + + ret = scsi_bsg_map_user_buffer(req, ioucmd, issue_flags, + gfp_mask, is_write, buf_addr, + buf_len); if (ret) goto out_free_req; pdu->bio = req->bio; -- 2.25.1