On 2022/05/27 14:51, Dongliang Mu wrote:
Hi maintainers,
I found a NPD(Null Pointer Dereference) in sd_zbc_release_disk function.
There are two definitions of sd_zbc_release_disk:
#ifdef CONFIG_BLK_DEV_ZONED
void sd_zbc_release_disk(struct scsi_disk *sdkp);
#else /* CONFIG_BLK_DEV_ZONED */
static inline void sd_zbc_release_disk(struct scsi_disk *sdkp) {}
#endif
When CONFIG_BLK_DEV_ZONED=y, the function implementation is as follows:
void sd_zbc_release_disk(struct scsi_disk *sdkp)
{
if (sd_is_zoned(sdkp))
sd_zbc_clear_zone_info(sdkp);
}
static inline int sd_is_zoned(struct scsi_disk *sdkp)
{
return sdkp->zoned == 1 || sdkp->device->type == TYPE_ZBC;
}
In drivers/scsi/sd.c, sd_probe() allocates sdkp with kzalloc(). If
errors occurred before the assignment "sdkp->device", after the
allocation, it will triggers a NPD in sd_is_zoned.
I am not familiar with kernel configuration. Does anyone have a
suggestion to fix this NPD?
I really appreciate any help you can provide.
Can you try this patch:
From 875899a114bce34f9549857ce87ea309b366b1cb Mon Sep 17 00:00:00 2001
From: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
Date: Fri, 27 May 2022 16:07:20 +0900
Subject: [PATCH] scsi: sd_zbc: Fix potential NULL pointer dereference
If sd_probe() sees an error before sdkp->device is initialized,
sd_zbc_release_disk() is called, which causes a NULL pointer dereference
when sd_is_zoned() is called. Avoid this by turning
sd_zbc_release_disk() into a nop if sdkp->device is NULL.
Reported-by: Dongliang Mu <mudongliangabcd@xxxxxxxxx>
Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
---
drivers/scsi/sd_zbc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c
index 5b9fad70aa88..236a766c8de4 100644
--- a/drivers/scsi/sd_zbc.c
+++ b/drivers/scsi/sd_zbc.c
@@ -804,7 +804,7 @@ static void sd_zbc_clear_zone_info(struct scsi_disk
*sdkp)
void sd_zbc_release_disk(struct scsi_disk *sdkp)
{
- if (sd_is_zoned(sdkp))
+ if (sdkp->device && sd_is_zoned(sdkp))
sd_zbc_clear_zone_info(sdkp);
}
--
2.36.1
--
Damien Le Moal
Western Digital Research
