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From: zhengbin <>
To: <>, <>,
Cc: <>, <>
Subject: [PATCH] scsi: core: fix uninit-value access of variable sshdr
Date: Thu, 10 Oct 2019 20:05:43 +0800
Message-ID: <> (raw)

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:
  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 <>
 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 ?

             reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-10 12:05 zhengbin [this message]
2019-10-10 17:03 ` Bart Van Assche
2019-10-11  3:07   ` zhengbin (A)
2019-10-11 17:15     ` Bart Van Assche
2019-10-11 17:17 ` Bart Van Assche

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