On 2019/10/17 8:05, Finn Thain wrote: > On Sat, 12 Oct 2019, 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: sr_do_ioctl should check whether sshdr is valid, fix this >> >> Signed-off-by: zhengbin <zhengbi...@huawei.com> >> --- >> v1->v2: modify the comments suggested by Bart >> v2->v3: fix bug in sr_do_ioctl >> drivers/scsi/scsi_lib.c | 7 +++++++ >> drivers/scsi/sr_ioctl.c | 5 +++++ >> 2 files changed, 12 insertions(+) >> >> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c >> index 5447738..d5e29c5 100644 >> --- a/drivers/scsi/scsi_lib.c >> +++ b/drivers/scsi/scsi_lib.c >> @@ -255,6 +255,13 @@ int __scsi_execute(struct scsi_device *sdev, const >> unsigned char *cmd, >> struct scsi_request *rq; >> int ret = DRIVER_ERROR << 24; >> >> + /* >> + * Zero-initialize sshdr for those callers that check the *sshdr >> + * contents even if no sense data is available. >> + */ >> + 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); > Does this have any effect? It appears __scsi_execute() calls > scsi_normalize_sense(), which already does > memset(sshdr, 0, sizeof(struct scsi_sense_hdr)).
__scsi_execute if (IS_ERR(req)) -->not init return ret; if (bufflen && ...) -->not init goto out; scsi_normalize_sense >
