diff mbox series

[v3] scsi: core: fix uninit-value access of variable sshdr

Message ID 1570850706-12063-1-git-send-email-zhengbin13@huawei.com (mailing list archive)
State Superseded
Headers show
Series [v3] scsi: core: fix uninit-value access of variable sshdr | expand

Commit Message

Zheng Bin Oct. 12, 2019, 3:25 a.m. UTC 
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@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(+)

--
2.7.4

Comments

Finn Thain Oct. 17, 2019, 12:05 a.m. UTC | #1 
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 <zhengbin13@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)).
Zheng Bin Oct. 17, 2019, 1:16 a.m. UTC | #2 
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 <zhengbin13@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

>
Bart Van Assche Oct. 17, 2019, 2:45 a.m. UTC | #3 
On 2019-10-11 20:25, zhengbin wrote:
> 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);

Although I don't have a strong opinion about this, I'm still wondering
whether 'sshdr' should be initialized in __scsi_execute() or by its caller.

> 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;

Shouldn't this be a separate patch?

Thanks,

Bart.
Zheng Bin Oct. 17, 2019, 3:26 a.m. UTC | #4 
On 2019/10/17 10:45, Bart Van Assche wrote:
> On 2019-10-11 20:25, zhengbin wrote:
>> 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);
> Although I don't have a strong opinion about this, I'm still wondering
> whether 'sshdr' should be initialized in __scsi_execute() or by its caller.
@jejb, @martin, any suggestion?
>
>> 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;
> Shouldn't this be a separate patch?
OK, will send a separate patch
>
> Thanks,
>
> Bart.
>
> .
>
diff mbox series

Patch

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;