From: Jason Yan <yanaijie@xxxxxxxxxx> commit d9a434fa0c12ed5f7afe1e9dd30003ab5d059b85 upstream. As explained in SG_IO howto[1]: "If iovec_count is non-zero then 'dxfer_len' should be equal to the sum of iov_len lengths. If not, the minimum of the two is the transfer length." When iovec_count is non-zero and dxfer_len is zero, the sg_io() just genarated a null bio, and finally caused a warning below. To fix it, skip generating a bio for this request if dxfer_len is zero. [1] https://tldp.org/HOWTO/SCSI-Generic-HOWTO/x198.html WARNING: CPU: 2 PID: 3643 at drivers/scsi/scsi_lib.c:1032 scsi_alloc_sgtables+0xc7d/0xf70 drivers/scsi/scsi_lib.c:1032 Modules linked in: CPU: 2 PID: 3643 Comm: syz-executor397 Not tainted 5.17.0-rc3-syzkaller-00316-gb81b1829e7e3 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-204/01/2014 RIP: 0010:scsi_alloc_sgtables+0xc7d/0xf70 drivers/scsi/scsi_lib.c:1032 Code: e7 fc 31 ff 44 89 f6 e8 c1 4e e7 fc 45 85 f6 0f 84 1a f5 ff ff e8 93 4c e7 fc 83 c5 01 0f b7 ed e9 0f f5 ff ff e8 83 4c e7 fc <0f> 0b 41 bc 0a 00 00 00 e9 2b fb ff ff 41 bc 09 00 00 00 e9 20 fb RSP: 0018:ffffc90000d07558 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff88801bfc96a0 RCX: 0000000000000000 RDX: ffff88801c876000 RSI: ffffffff849060bd RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff849055b9 R11: 0000000000000000 R12: ffff888012b8c000 R13: ffff88801bfc9580 R14: 0000000000000000 R15: ffff88801432c000 FS: 00007effdec8e700(0000) GS:ffff88802cc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007effdec6d718 CR3: 00000000206d6000 CR4: 0000000000150ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> scsi_setup_scsi_cmnd drivers/scsi/scsi_lib.c:1219 [inline] scsi_prepare_cmd drivers/scsi/scsi_lib.c:1614 [inline] scsi_queue_rq+0x283e/0x3630 drivers/scsi/scsi_lib.c:1730 blk_mq_dispatch_rq_list+0x6ea/0x22e0 block/blk-mq.c:1851 __blk_mq_sched_dispatch_requests+0x20b/0x410 block/blk-mq-sched.c:299 blk_mq_sched_dispatch_requests+0xfb/0x180 block/blk-mq-sched.c:332 __blk_mq_run_hw_queue+0xf9/0x350 block/blk-mq.c:1968 __blk_mq_delay_run_hw_queue+0x5b6/0x6c0 block/blk-mq.c:2045 blk_mq_run_hw_queue+0x30f/0x480 block/blk-mq.c:2096 blk_mq_sched_insert_request+0x340/0x440 block/blk-mq-sched.c:451 blk_execute_rq+0xcc/0x340 block/blk-mq.c:1231 sg_io+0x67c/0x1210 drivers/scsi/scsi_ioctl.c:485 scsi_ioctl_sg_io drivers/scsi/scsi_ioctl.c:866 [inline] scsi_ioctl+0xa66/0x1560 drivers/scsi/scsi_ioctl.c:921 sd_ioctl+0x199/0x2a0 drivers/scsi/sd.c:1576 blkdev_ioctl+0x37a/0x800 block/ioctl.c:588 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7effdecdc5d9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 81 14 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007effdec8e2f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007effded664c0 RCX: 00007effdecdc5d9 RDX: 0000000020002300 RSI: 0000000000002285 RDI: 0000000000000004 RBP: 00007effded34034 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003 R13: 00007effded34054 R14: 2f30656c69662f2e R15: 00007effded664c8 Link: https://lore.kernel.org/r/20220720025120.3226770-1-yanaijie@xxxxxxxxxx Fixes: 25636e282fe9 ("block: fix SG_IO vector request data length handling") Reported-by: syzbot+d44b35ecfb807e5af0b5@xxxxxxxxxxxxxxxxxxxxxxxxx Reviewed-by: Christoph Hellwig <hch@xxxxxx> Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx> Signed-off-by: Jason Yan <yanaijie@xxxxxxxxxx> Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/scsi/scsi_ioctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/scsi/scsi_ioctl.c +++ b/drivers/scsi/scsi_ioctl.c @@ -457,7 +457,7 @@ static int sg_io(struct scsi_device *sde goto out_free_cdb; ret = 0; - if (hdr->iovec_count) { + if (hdr->iovec_count && hdr->dxfer_len) { struct iov_iter i; struct iovec *iov = NULL;
