From 17b49bcbf8351d3dbe57204468ac34f033ed60bc Mon Sep 17 00:00:00 2001 From: Damien Le Moal Date: Fri, 20 Aug 2021 16:02:53 +0900 Subject: scsi: core: Fix scsi_mode_sense() buffer length handling Several problems exist with scsi_mode_sense() buffer length handling: 1) The allocation length field of the MODE SENSE(10) command is 16-bits, occupying bytes 7 and 8 of the CDB. With this command, access to mode pages larger than 255 bytes is thus possible. However, the CDB allocation length field is set by assigning len to byte 8 only, thus truncating buffer length larger than 255. 2) If scsi_mode_sense() is called with len smaller than 8 with sdev->use_10_for_ms set, or smaller than 4 otherwise, the buffer length is increased to 8 and 4 respectively, and the buffer is zero filled with these increased values, thus corrupting the memory following the buffer. Fix these 2 problems by using put_unaligned_be16() to set the allocation length field of MODE SENSE(10) CDB and by returning an error when len is too small. Furthermore, if len is larger than 255B, always try MODE SENSE(10) first, even if the device driver did not set sdev->use_10_for_ms. In case of invalid opcode error for MODE SENSE(10), access to mode pages larger than 255 bytes are not retried using MODE SENSE(6). To avoid buffer length overflows for the MODE_SENSE(10) case, check that len is smaller than 65535 bytes. While at it, also fix the folowing: * Use get_unaligned_be16() to retrieve the mode data length and block descriptor length fields of the mode sense reply header instead of using an open coded calculation. * Fix the kdoc dbd argument explanation: the DBD bit stands for Disable Block Descriptor, which is the opposite of what the dbd argument description was. Link: https://lore.kernel.org/r/20210820070255.682775-2-damien.lemoal@wdc.com Signed-off-by: Damien Le Moal Signed-off-by: Martin K. Petersen --- drivers/scsi/scsi_lib.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) (limited to 'drivers/scsi/scsi_lib.c') diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 572673873ddf..701d8e8480f2 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -2075,7 +2075,7 @@ EXPORT_SYMBOL_GPL(scsi_mode_select); /** * scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary. * @sdev: SCSI device to be queried - * @dbd: set if mode sense will allow block descriptors to be returned + * @dbd: set to prevent mode sense from returning block descriptors * @modepage: mode page being requested * @buffer: request buffer (may not be smaller than eight bytes) * @len: length of request buffer. @@ -2110,18 +2110,18 @@ scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage, sshdr = &my_sshdr; retry: - use_10_for_ms = sdev->use_10_for_ms; + use_10_for_ms = sdev->use_10_for_ms || len > 255; if (use_10_for_ms) { - if (len < 8) - len = 8; + if (len < 8 || len > 65535) + return -EINVAL; cmd[0] = MODE_SENSE_10; - cmd[8] = len; + put_unaligned_be16(len, &cmd[7]); header_length = 8; } else { if (len < 4) - len = 4; + return -EINVAL; cmd[0] = MODE_SENSE; cmd[4] = len; @@ -2145,9 +2145,15 @@ scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage, if ((sshdr->sense_key == ILLEGAL_REQUEST) && (sshdr->asc == 0x20) && (sshdr->ascq == 0)) { /* - * Invalid command operation code + * Invalid command operation code: retry using + * MODE SENSE(6) if this was a MODE SENSE(10) + * request, except if the request mode page is + * too large for MODE SENSE single byte + * allocation length field. */ if (use_10_for_ms) { + if (len > 255) + return -EIO; sdev->use_10_for_ms = 0; goto retry; } @@ -2171,12 +2177,11 @@ scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage, data->longlba = 0; data->block_descriptor_length = 0; } else if (use_10_for_ms) { - data->length = buffer[0]*256 + buffer[1] + 2; + data->length = get_unaligned_be16(&buffer[0]) + 2; data->medium_type = buffer[2]; data->device_specific = buffer[3]; data->longlba = buffer[4] & 0x01; - data->block_descriptor_length = buffer[6]*256 - + buffer[7]; + data->block_descriptor_length = get_unaligned_be16(&buffer[6]); } else { data->length = buffer[0] + 1; data->medium_type = buffer[1]; -- cgit From a7d6840bed0c2b16ac3071b74b5fcf08fc488241 Mon Sep 17 00:00:00 2001 From: Damien Le Moal Date: Fri, 20 Aug 2021 16:02:54 +0900 Subject: scsi: core: Fix scsi_mode_select() buffer length handling The MODE SELECT(6) command allows handling mode page buffers that are up to 255 bytes, including the 4 byte header needed in front of the page buffer. For requests larger than this limit, automatically use the MODE SELECT(10) command. In both cases, since scsi_mode_select() adds the mode select page header, checks on the buffer length value must include this header size to avoid overflows of the command CDB allocation length field. While at it, use put_unaligned_be16() for setting the header block descriptor length and CDB allocation length when using MODE SELECT(10). [mkp: fix MODE SENSE vs. MODE SELECT confusion] Link: https://lore.kernel.org/r/20210820070255.682775-3-damien.lemoal@wdc.com Signed-off-by: Damien Le Moal Signed-off-by: Martin K. Petersen --- drivers/scsi/scsi_lib.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) (limited to 'drivers/scsi/scsi_lib.c') diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 701d8e8480f2..dcf105287a76 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -2026,8 +2026,15 @@ scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage, memset(cmd, 0, sizeof(cmd)); cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0); - if (sdev->use_10_for_ms) { - if (len > 65535) + /* + * Use MODE SELECT(10) if the device asked for it or if the mode page + * and the mode select header cannot fit within the maximumm 255 bytes + * of the MODE SELECT(6) command. + */ + if (sdev->use_10_for_ms || + len + 4 > 255 || + data->block_descriptor_length > 255) { + if (len > 65535 - 8) return -EINVAL; real_buffer = kmalloc(8 + len, GFP_KERNEL); if (!real_buffer) @@ -2040,15 +2047,13 @@ scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage, real_buffer[3] = data->device_specific; real_buffer[4] = data->longlba ? 0x01 : 0; real_buffer[5] = 0; - real_buffer[6] = data->block_descriptor_length >> 8; - real_buffer[7] = data->block_descriptor_length; + put_unaligned_be16(data->block_descriptor_length, + &real_buffer[6]); cmd[0] = MODE_SELECT_10; - cmd[7] = len >> 8; - cmd[8] = len; + put_unaligned_be16(len, &cmd[7]); } else { - if (len > 255 || data->block_descriptor_length > 255 || - data->longlba) + if (data->longlba) return -EINVAL; real_buffer = kmalloc(4 + len, GFP_KERNEL); -- cgit From e9076e7f23aa087f8b7257f3be9e9586f341e3b1 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Wed, 29 Sep 2021 11:23:18 -0700 Subject: scsi: core: Fix spelling in a source code comment The typo in this source code comment makes the comment confusing. Clear up the confusion by fixing the typo. Link: https://lore.kernel.org/r/20210929182318.2060489-1-bvanassche@acm.org Fixes: bc85dc500f9d ("scsi: remove scsi_end_request") Cc: Christoph Hellwig Signed-off-by: Bart Van Assche Signed-off-by: Martin K. Petersen --- drivers/scsi/scsi_lib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/scsi/scsi_lib.c') diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index dcf105287a76..5f5ad22512f5 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -949,7 +949,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) /* * If there had been no error, but we have leftover bytes in the - * requeues just queue the command up again. + * request just queue the command up again. */ if (likely(result == 0)) scsi_io_completion_reprep(cmd, q); -- cgit From bf23e619039d360d503b7282d030daf2277a5d47 Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Thu, 7 Oct 2021 13:27:56 -0700 Subject: scsi: core: Use a structure member to track the SCSI command submitter Conditional statements are faster than indirect calls. Use a structure member to track the SCSI command submitter such that later patches can call scsi_done(scmd) instead of scmd->scsi_done(scmd). The asymmetric behavior that scsi_send_eh_cmnd() sets the submission context to the SCSI error handler and that it does not restore the submission context to the SCSI core is retained. Link: https://lore.kernel.org/r/20211007202923.2174984-2-bvanassche@acm.org Cc: Hannes Reinecke Cc: Ming Lei Cc: Christoph Hellwig Reviewed-by: Benjamin Block Reviewed-by: Bean Huo Signed-off-by: Bart Van Assche Signed-off-by: Martin K. Petersen --- drivers/scsi/scsi_lib.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'drivers/scsi/scsi_lib.c') diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 5f5ad22512f5..3fd24144b805 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1577,6 +1577,15 @@ static blk_status_t scsi_prepare_cmd(struct request *req) static void scsi_mq_done(struct scsi_cmnd *cmd) { + switch (cmd->submitter) { + case SUBMITTED_BY_BLOCK_LAYER: + break; + case SUBMITTED_BY_SCSI_ERROR_HANDLER: + return scsi_eh_done(cmd); + case SUBMITTED_BY_SCSI_RESET_IOCTL: + return; + } + if (unlikely(blk_should_fake_timeout(scsi_cmd_to_rq(cmd)->q))) return; if (unlikely(test_and_set_bit(SCMD_STATE_COMPLETE, &cmd->state))) @@ -1683,6 +1692,7 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, scsi_set_resid(cmd, 0); memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE); + cmd->submitter = SUBMITTED_BY_BLOCK_LAYER; cmd->scsi_done = scsi_mq_done; blk_mq_start_request(req); -- cgit From a710eacb9d13cb5d9eb5341ebc6fc8f7b96f8c6f Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Thu, 7 Oct 2021 13:27:57 -0700 Subject: scsi: core: Rename scsi_mq_done() into scsi_done() and export it Since the removal of the legacy block layer there is only one completion function left in the SCSI core, namely scsi_mq_done(). Rename it into scsi_done(). Export that function to allow SCSI LLDs to call it directly. Link: https://lore.kernel.org/r/20211007202923.2174984-3-bvanassche@acm.org Reviewed-by: Benjamin Block Reviewed-by: Bean Huo Signed-off-by: Bart Van Assche Signed-off-by: Martin K. Petersen --- drivers/scsi/scsi_lib.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'drivers/scsi/scsi_lib.c') diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 3fd24144b805..f690a2da21ea 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1575,7 +1575,7 @@ static blk_status_t scsi_prepare_cmd(struct request *req) return scsi_cmd_to_driver(cmd)->init_command(cmd); } -static void scsi_mq_done(struct scsi_cmnd *cmd) +void scsi_done(struct scsi_cmnd *cmd) { switch (cmd->submitter) { case SUBMITTED_BY_BLOCK_LAYER: @@ -1593,6 +1593,7 @@ static void scsi_mq_done(struct scsi_cmnd *cmd) trace_scsi_dispatch_cmd_done(cmd); blk_mq_complete_request(scsi_cmd_to_rq(cmd)); } +EXPORT_SYMBOL(scsi_done); static void scsi_mq_put_budget(struct request_queue *q, int budget_token) { @@ -1693,7 +1694,7 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, scsi_set_resid(cmd, 0); memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE); cmd->submitter = SUBMITTED_BY_BLOCK_LAYER; - cmd->scsi_done = scsi_mq_done; + cmd->scsi_done = scsi_done; blk_mq_start_request(req); reason = scsi_dispatch_cmd(cmd); -- cgit From 11b68e36b16752ae3a48dc16229958ebc9bb324a Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Thu, 7 Oct 2021 13:46:11 -0700 Subject: scsi: core: Call scsi_done directly Conditional statements are faster than indirect calls. Hence call scsi_done() directly. Since this patch removes the last user of the scsi_done member, also remove that data structure member. Link: https://lore.kernel.org/r/20211007204618.2196847-11-bvanassche@acm.org Reviewed-by: Benjamin Block Reviewed-by: Bean Huo Signed-off-by: Bart Van Assche Signed-off-by: Martin K. Petersen --- drivers/scsi/scsi_lib.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'drivers/scsi/scsi_lib.c') diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index f690a2da21ea..d0b7c6dc74f8 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1520,7 +1520,7 @@ static int scsi_dispatch_cmd(struct scsi_cmnd *cmd) return rtn; done: - cmd->scsi_done(cmd); + scsi_done(cmd); return 0; } @@ -1694,7 +1694,6 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, scsi_set_resid(cmd, 0); memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE); cmd->submitter = SUBMITTED_BY_BLOCK_LAYER; - cmd->scsi_done = scsi_done; blk_mq_start_request(req); reason = scsi_dispatch_cmd(cmd); -- cgit