FAILED: patch "[PATCH] scsi: ufs: bsg: Validate request_len before accessing request" failed to apply to 6.12-stable tree

[Sasha Levin <sashal@kernel.org>]

The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 42aa443718104d10dbdb6f258810b425eb2451f8
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261107052541-failed-6.12-42aa44371810@kernel.org' --subject-prefix 'PATCH 6.12.y' 'HEAD^..'

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From 42aa443718104d10dbdb6f258810b425eb2451f8 Mon Sep 17 00:00:00 2001
From: Stanley Jhu <stanleyjhu@google.com>
Date: Thu, 15 Oct 2026 08:18:53 +0800
Subject: [PATCH] scsi: ufs: bsg: Validate request_len before accessing request

ufs_bsg_request() and ufs_bsg_exec_advanced_rpmb_req() read the request
buffer without checking job->request_len, which userspace controls. A short
request causes an out-of-bounds read. Found by syzkaller.

Reject requests shorter than the structure each path reads.

Fixes: 64d4864714c2 ("scsi: ufs: bsg: Remove unnecessary length checkup")
Fixes: 6ff265fc5ef6 ("scsi: ufs: core: bsg: Add advanced RPMB support in ufs_bsg")
Cc: stable@vger.kernel.org
Reviewed-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Stanley Jhu <stanleyjhu@google.com>
Reviewed-by: Peter Wang <peter.wang@mediatek.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://patch.msgid.link/20261015001855.3450573-4-stanleyjhu@google.com
Signed-off-by: Martin K. Petersen (Oracle) <mkp@kernel.org>
---
 drivers/ufs/core/ufs_bsg.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/ufs/core/ufs_bsg.c b/drivers/ufs/core/ufs_bsg.c
index 545ef7b79ceb5..0db830e54ef0f 100644
--- a/drivers/ufs/core/ufs_bsg.c
+++ b/drivers/ufs/core/ufs_bsg.c
@@ -73,6 +73,9 @@ static int ufs_bsg_exec_advanced_rpmb_req(struct ufs_hba *hba, struct bsg_job *j
 	if (hba->ufs_version < ufshci_version(4, 0) || !hba->dev_info.b_advanced_rpmb_en)
 		return -EINVAL;
 
+	if (job->request_len < sizeof(*rpmb_request))
+		return -EINVAL;
+
 	if (rpmb_request->ehs_req.length != 2 || rpmb_request->ehs_req.ehs_type != 1)
 		return -EINVAL;
 
@@ -142,6 +145,11 @@ static int ufs_bsg_request(struct bsg_job *job)
 
 	memset(job->reply, 0, job->reply_len);
 
+	if (job->request_len < sizeof(*bsg_request)) {
+		ret = -EINVAL;
+		goto out_complete;
+	}
+
 	ufshcd_rpm_get_sync(hba);
 
 	msgcode = bsg_request->msgcode;
@@ -194,6 +202,7 @@ static int ufs_bsg_request(struct bsg_job *job)
 out:
 	ufshcd_rpm_put_sync(hba);
 	kfree(buff);
+out_complete:
 	bsg_reply->result = ret;
 	if (ret == 0)
 		job->reply_len = rpmb ? sizeof(struct ufs_rpmb_reply) :
-- 
2.53.0