[PATCH v3 01/18] scsi: ufs: Fix memory corruption by ufshcd_read_desc_param()

From: Bart Van Assche <bvanassche@acm.org>
To: "Martin K . Petersen" <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>,
	Bart Van Assche <bvanassche@acm.org>,
	"James E.J. Bottomley" <jejb@linux.ibm.com>,
	Can Guo <cang@codeaurora.org>,
	Stanley Chu <stanley.chu@mediatek.com>,
	Bean Huo <beanhuo@micron.com>, Avri Altman <avri.altman@wdc.com>,
	Asutosh Das <asutoshd@codeaurora.org>
Subject: [PATCH v3 01/18] scsi: ufs: Fix memory corruption by ufshcd_read_desc_param()
Date: Wed, 21 Jul 2021 20:34:22 -0700	[thread overview]
Message-ID: <20210722033439.26550-2-bvanassche@acm.org> (raw)
In-Reply-To: <20210722033439.26550-1-bvanassche@acm.org>

If param_offset > buff_len then the memcpy() statement in
ufshcd_read_desc_param() corrupts memory since it copies
256 + buff_len - param_offset bytes into a buffer with size buff_len.
Since param_offset < 256 this results in writing past the bound of the
output buffer.

Fixes: cbe193f6f093 ("scsi: ufs: Fix potential NULL pointer access during memcpy")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/ufs/ufshcd.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 064a44e628d6..6c251afe65f9 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -3418,9 +3418,11 @@ int ufshcd_read_desc_param(struct ufs_hba *hba,
 
 	if (is_kmalloc) {
 		/* Make sure we don't copy more data than available */
-		if (param_offset + param_size > buff_len)
-			param_size = buff_len - param_offset;
-		memcpy(param_read_buf, &desc_buf[param_offset], param_size);
+		if (param_offset >= buff_len)
+			ret = -EINVAL;
+		else
+			memcpy(param_read_buf, &desc_buf[param_offset],
+			       min_t(u32, param_size, buff_len - param_offset));
 	}
 out:
 	if (is_kmalloc)
