[PATCH v2] scsi: fix out of bounds error in /drivers/scsi

[jackysliu <1972843537@qq.com>]

6.15-stable review patch, vulnerability exists since v6.9

Out-of-bounds vulnerability found in ./drivers/scsi/sd.c
The vulnerability is found by  is found by Wukong-Agent
 (formerly Tencent Woodpecker), a code security AI agent,
 through static code analysis. 

sd_read_block_limits_ext Function Due to Unreasonable boundary checks.
Out-of-bounds read vulnerability exists in the
Linux kernel's SCSI disk driver (./drivers/scsi/sd.c).
The flaw occurs in the sd_read_block_limits_ext function
 when processing Vital Product Data (VPD) page B7 (Block Limits Extension)
 responses from storage devices

A maliciously crafted 4-byte VPD page (0xB7) would cause Out-of-Bounds
Memory Read, leading to potential system Instability 
and Driver State Corruption.


Signed-off-by: jackysliu <1972843537@qq.com>
---
 drivers/scsi/sd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 3f6e87705b62..eeaa6af294b8 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3384,7 +3384,7 @@ static void sd_read_block_limits_ext(struct scsi_disk *sdkp)
 
 	rcu_read_lock();
 	vpd = rcu_dereference(sdkp->device->vpd_pgb7);
-	if (vpd && vpd->len >= 2)
+	if (vpd && vpd->len >= 6)
 		sdkp->rscs = vpd->data[5] & 1;
 	rcu_read_unlock();
 }
-- 
2.43.5