Since the scsi subsystem adopted the blk-mq API, a host with zero sg_tablesize crashes with a NULL pointer dereference.
blk_queue_max_segments: set to minimum 1 scsi 0:0:0:0: Direct-Access QEMU QEMU HARDDISK 2.5+ PQ: 0 ANSI: 5 scsi target0:0:0: Beginning Domain Validation scsi target0:0:0: Domain Validation skipping write tests scsi target0:0:0: Ending Domain Validation blk_queue_max_segments: set to minimum 1 scsi 0:0:1:0: Direct-Access QEMU QEMU HARDDISK 2.5+ PQ: 0 ANSI: 5 scsi target0:0:1: Beginning Domain Validation scsi target0:0:1: Domain Validation skipping write tests scsi target0:0:1: Ending Domain Validation blk_queue_max_segments: set to minimum 1 scsi 0:0:2:0: CD-ROM QEMU QEMU CD-ROM 2.5+ PQ: 0 ANSI: 5 scsi target0:0:2: Beginning Domain Validation scsi target0:0:2: Domain Validation skipping write tests scsi target0:0:2: Ending Domain Validation blk_queue_max_segments: set to minimum 1 blk_queue_max_segments: set to minimum 1 blk_queue_max_segments: set to minimum 1 blk_queue_max_segments: set to minimum 1 sr 0:0:2:0: Power-on or device reset occurred sd 0:0:0:0: Power-on or device reset occurred sd 0:0:1:0: Power-on or device reset occurred sd 0:0:0:0: [sda] 10485762 512-byte logical blocks: (5.37 GB/5.00 GiB) sd 0:0:0:0: [sda] Write Protect is off sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA Unable to handle kernel NULL pointer dereference at virtual address (ptrval) Oops: 00000000 Modules linked in: PC: [<001cd874>] blk_mq_free_request+0x66/0xe2 SR: 2004 SP: (ptrval) a2: 00874520 d0: 00000000 d1: 00000000 d2: 009ba800 d3: 00000000 d4: 00000000 d5: 08000002 a0: 0087be68 a1: 009a81e0 Process kworker/u2:2 (pid: 15, task=(ptrval)) Frame format=7 eff addr=0000007a ssw=0505 faddr=0000007a wb 1 stat/addr/data: 0000 00000000 00000000 wb 2 stat/addr/data: 0000 00000000 00000000 wb 3 stat/addr/data: 0000 0000007a 00000000 push data: 00000000 00000000 00000000 00000000 Stack from 0087bd98: 00000002 00000000 0087be72 009a7820 0087bdb4 001c4f6c 009a7820 0087bdd4 0024d200 009a7820 0024d0dc 0087be72 009baa00 0087be68 009a5000 0087be7c 00265d10 009a5000 0087be72 00000003 00000000 00000000 00000000 0087be68 00000bb8 00000005 00000000 00000000 00000000 00000000 00265c56 00000000 009ba60c 0036ddf4 00000002 ffffffff 009baa00 009ba600 009a50d6 0087be74 00227ba0 009baa08 00000001 009baa08 009ba60c 0036ddf4 00000000 00000000 Call Trace: [<001c4f6c>] blk_put_request+0xe/0x14 [<0024d200>] __scsi_execute+0x124/0x174 [<0024d0dc>] __scsi_execute+0x0/0x174 [<00265d10>] sd_revalidate_disk+0xba/0x1f02 [<00265c56>] sd_revalidate_disk+0x0/0x1f02 [<0036ddf4>] strlen+0x0/0x22 [<00227ba0>] device_add+0x3da/0x604 [<0036ddf4>] strlen+0x0/0x22 [<00267e64>] sd_probe+0x30c/0x4b4 [<0002da44>] process_one_work+0x0/0x402 [<0022b978>] really_probe+0x226/0x354 [<0022bc34>] driver_probe_device+0xa4/0xf0 [<0002da44>] process_one_work+0x0/0x402 [<0022bcd0>] __driver_attach_async_helper+0x50/0x70 [<00035dae>] async_run_entry_fn+0x36/0x130 [<0002db88>] process_one_work+0x144/0x402 [<0002e1aa>] worker_thread+0x0/0x570 [<0002e29a>] worker_thread+0xf0/0x570 [<0002e1aa>] worker_thread+0x0/0x570 [<003768d8>] schedule+0x0/0xb8 [<0003f58c>] __init_waitqueue_head+0x0/0x12 [<00033e92>] kthread+0xc2/0xf6 [<000331e8>] kthread_parkme+0x0/0x4e [<003768d8>] schedule+0x0/0xb8 [<00033dd0>] kthread+0x0/0xf6 [<00002c10>] ret_from_kernel_thread+0xc/0x14 Code: 0280 0006 0800 56c0 4400 0280 0000 00ff <52b4> 0c3a 082b 0006 0013 6706 2042 53a8 00c4 4ab9 0047 3374 6640 202d 000c 670c Disabling lock debugging due to kernel taint
Avoid this by setting sg_tablesize = 1.
Cc: stable@vger.kernel.org # 4.19+ Reported-and-tested-by: Michael Schmitz schmitzmic@gmail.com Reviewed-by: Michael Schmitz schmitzmic@gmail.com References: commit 68ab2d76e4be ("scsi: cxlflash: Set sg_tablesize to 1 instead of SG_NONE") Signed-off-by: Finn Thain fthain@telegraphics.com.au --- drivers/scsi/atari_scsi.c | 6 +++--- drivers/scsi/mac_scsi.c | 2 +- drivers/scsi/sun3_scsi.c | 4 ++-- 3 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/scsi/atari_scsi.c b/drivers/scsi/atari_scsi.c index e809493d0d06..a82b63a66635 100644 --- a/drivers/scsi/atari_scsi.c +++ b/drivers/scsi/atari_scsi.c @@ -742,7 +742,7 @@ static int __init atari_scsi_probe(struct platform_device *pdev) atari_scsi_template.sg_tablesize = SG_ALL; } else { atari_scsi_template.can_queue = 1; - atari_scsi_template.sg_tablesize = SG_NONE; + atari_scsi_template.sg_tablesize = 1; }
if (setup_can_queue > 0) @@ -751,8 +751,8 @@ static int __init atari_scsi_probe(struct platform_device *pdev) if (setup_cmd_per_lun > 0) atari_scsi_template.cmd_per_lun = setup_cmd_per_lun;
- /* Leave sg_tablesize at 0 on a Falcon! */ - if (ATARIHW_PRESENT(TT_SCSI) && setup_sg_tablesize >= 0) + /* Don't increase sg_tablesize on Falcon! */ + if (ATARIHW_PRESENT(TT_SCSI) && setup_sg_tablesize > 0) atari_scsi_template.sg_tablesize = setup_sg_tablesize;
if (setup_hostid >= 0) { diff --git a/drivers/scsi/mac_scsi.c b/drivers/scsi/mac_scsi.c index 9c5566217ef6..b5dde9d0d054 100644 --- a/drivers/scsi/mac_scsi.c +++ b/drivers/scsi/mac_scsi.c @@ -464,7 +464,7 @@ static int __init mac_scsi_probe(struct platform_device *pdev) mac_scsi_template.can_queue = setup_can_queue; if (setup_cmd_per_lun > 0) mac_scsi_template.cmd_per_lun = setup_cmd_per_lun; - if (setup_sg_tablesize >= 0) + if (setup_sg_tablesize > 0) mac_scsi_template.sg_tablesize = setup_sg_tablesize; if (setup_hostid >= 0) mac_scsi_template.this_id = setup_hostid & 7; diff --git a/drivers/scsi/sun3_scsi.c b/drivers/scsi/sun3_scsi.c index 955e4c938d49..701b842296f0 100644 --- a/drivers/scsi/sun3_scsi.c +++ b/drivers/scsi/sun3_scsi.c @@ -501,7 +501,7 @@ static struct scsi_host_template sun3_scsi_template = { .eh_host_reset_handler = sun3scsi_host_reset, .can_queue = 16, .this_id = 7, - .sg_tablesize = SG_NONE, + .sg_tablesize = 1, .cmd_per_lun = 2, .dma_boundary = PAGE_SIZE - 1, .cmd_size = NCR5380_CMD_SIZE, @@ -523,7 +523,7 @@ static int __init sun3_scsi_probe(struct platform_device *pdev) sun3_scsi_template.can_queue = setup_can_queue; if (setup_cmd_per_lun > 0) sun3_scsi_template.cmd_per_lun = setup_cmd_per_lun; - if (setup_sg_tablesize >= 0) + if (setup_sg_tablesize > 0) sun3_scsi_template.sg_tablesize = setup_sg_tablesize; if (setup_hostid >= 0) sun3_scsi_template.this_id = setup_hostid & 7;