On 10/10/19 5:05 AM, zhengbin wrote:
kmsan report a warning in 5.1-rc4: BUG: KMSAN: uninit-value in sr_get_events drivers/scsi/sr.c:207 [inline] BUG: KMSAN: uninit-value in sr_check_events+0x2cf/0x1090 drivers/scsi/sr.c:243 CPU: 1 PID: 13858 Comm: syz-executor.0 Tainted: G B 5.1.0-rc4+ #8 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x173/0x1d0 lib/dump_stack.c:113 kmsan_report+0x131/0x2a0 mm/kmsan/kmsan.c:619 __msan_warning+0x7a/0xf0 mm/kmsan/kmsan_instr.c:310 sr_get_events drivers/scsi/sr.c:207 [inline] sr_check_events+0x2cf/0x1090 drivers/scsi/sr.c:243 The reason is as follows: sr_get_events struct scsi_sense_hdr sshdr; -->uninit scsi_execute_req -->If fail, will not set sshdr scsi_sense_valid(&sshdr) -->access sshdr We can init sshdr in sr_get_events, but there have many callers of scsi_execute, scsi_execute_req, we have to troubleshoot all callers, the simpler way is init sshdr in __scsi_execute. BTW: we can't just init sshdr->response_code, sr_do_ioctl use sshdr->sense_key(Need to troubleshoot all callers) Signed-off-by: zhengbin <zhengbin13@xxxxxxxxxx> --- drivers/scsi/scsi_lib.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 5447738..037fb2a 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -255,6 +255,12 @@ int __scsi_execute(struct scsi_device *sdev, const unsigned char *cmd, struct scsi_request *rq; int ret = DRIVER_ERROR << 24; + /* + * need to initial sshdr to avoid uninit-value access + */ + if (sshdr) + memset(sshdr, 0, sizeof(struct scsi_sense_hdr)); + req = blk_get_request(sdev->request_queue, data_direction == DMA_TO_DEVICE ? REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, BLK_MQ_REQ_PREEMPT);
From SAM-5: "Sense data shall be made available by the logical unit if a command terminates with CHECK CONDITION status or other conditions (e.g., the processing of a REQUEST SENSE command). The format, content, and conditions under which sense data shall be prepared by the logical unit are as defined in this standard, SPC-4, the applicable command standard, and the applicable SCSI transport protocol standard."
Apparently sr_check_events() submits a GET EVENT STATUS NOTIFICATION command and it even evaluates the sense data if that command succeeded. I'm not aware of other scsi_execute() callers that do this. So I'm not sure that modifying __scsi_execute() is the best approach. I'm wondering whether the sr driver should be fixed instead of modifying __scsi_execute().
Thanks, Bart.
