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 <zhengbin13@xxxxxxxxxx>
---
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);
diff --git a/drivers/scsi/sr_ioctl.c b/drivers/scsi/sr_ioctl.c
index ffcf902..335cfdd 100644
--- a/drivers/scsi/sr_ioctl.c
+++ b/drivers/scsi/sr_ioctl.c
@@ -206,6 +206,11 @@ int sr_do_ioctl(Scsi_CD *cd, struct packet_command *cgc)
/* Minimal error checking. Ignore cases we know about, and report the rest. */
if (driver_byte(result) != 0) {
+ if (!scsi_sense_valid(sshdr)) {
+ err = -EIO;
+ goto out;
+ }
+
switch (sshdr->sense_key) {
case UNIT_ATTENTION:
SDev->changed = 1;
--
2.7.4
