From: Laibin Qiu qiulaibin@huawei.com
hulk inclusion category: bugfix bugzilla: 179896 https://gitee.com/openeuler/kernel/issues/I4DDEL
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In passthrough path. If the command size for ioctl request from userspace is 0. The original process will get cmd_len from cmd->cmnd, but It has not been assigned at this time. So it will trigger a NULL pointer BUG.
------------[ cut here ]------------ BUG: kernel NULL pointer dereference, address: 0000000000000000 PF: supervisor read access in kernel mode PF: error_code(0x0000) - not-present page RIP: 0010:scsi_queue_rq+0xcb2/0x12b0 Call Trace: blk_mq_dispatch_rq_list+0x541/0xe90 __blk_mq_sched_dispatch_requests+0x1fe/0x2b0 blk_mq_sched_dispatch_requests+0xbf/0x130 __blk_mq_run_hw_queue+0x15b/0x230 __blk_mq_delay_run_hw_queue+0x18f/0x320 blk_mq_run_hw_queue+0x252/0x280 blk_mq_sched_insert_request+0x228/0x260 blk_execute_rq+0x111/0x160 sg_io+0x51a/0x740 scsi_cmd_ioctl+0x533/0x910 scsi_cmd_blk_ioctl+0xa1/0xb0 cdrom_ioctl+0x3f/0x2510 sr_block_ioctl+0x142/0x180 blkdev_ioctl+0x398/0x450 block_ioctl+0x6d/0x80 __se_sys_ioctl+0xd1/0x140 __x64_sys_ioctl+0x3f/0x50 do_syscall_64+0x37/0x50 entry_SYSCALL_64_after_hwframe+0x44/0xa9
We can trigger front BUG by ioctl blow. ------------[ cut here ]------------
sg_io_hdr_t *addr;
addr = malloc(sizeof(sg_io_hdr_t)); memset(addr, 0, sizeof(sg_io_hdr_t)); addr->interface_id = 'S';
fd = open(/dev/sr0, O_RDONLY); // open a CD_ROM dev
ioctl(fd, SG_IO, addr); // all zero sg_io_hdr_t will trigger this bug
Fixes: 2ceda20f0a99a ("scsi: core: Move command size detection out of the fast path") Signed-off-by: Laibin Qiu qiulaibin@huawei.com Reviewed-by: Jason Yan yanaijie@huawei.com
Signed-off-by: Chen Jun chenjun102@huawei.com --- drivers/scsi/scsi_lib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index d89db29fa829..b26c922bd65d 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1193,9 +1193,9 @@ static blk_status_t scsi_setup_scsi_cmnd(struct scsi_device *sdev, }
cmd->cmd_len = scsi_req(req)->cmd_len; + cmd->cmnd = scsi_req(req)->cmd; if (cmd->cmd_len == 0) cmd->cmd_len = scsi_command_size(cmd->cmnd); - cmd->cmnd = scsi_req(req)->cmd; cmd->transfersize = blk_rq_bytes(req); cmd->allowed = scsi_req(req)->retries; return BLK_STS_OK;