This is a note to let you know that I've just added the patch titled
scsi: sg: Avoid sg device teardown race
to the 6.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
scsi-sg-avoid-sg-device-teardown-race.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 959f530354e02b9de6f7881102dbae6053e4c6a4
Author: Alexander Wetzel <Alexander@xxxxxxxxxxxxxx>
Date: Wed Mar 20 22:30:32 2024 +0100
scsi: sg: Avoid sg device teardown race
[ Upstream commit 27f58c04a8f438078583041468ec60597841284d ]
sg_remove_sfp_usercontext() must not use sg_device_destroy() after calling
scsi_device_put().
sg_device_destroy() is accessing the parent scsi_device request_queue which
will already be set to NULL when the preceding call to scsi_device_put()
removed the last reference to the parent scsi_device.
The resulting NULL pointer exception will then crash the kernel.
Link: https://lore.kernel.org/r/20240305150509.23896-1-Alexander@xxxxxxxxxxxxxx
Fixes: db59133e9279 ("scsi: sg: fix blktrace debugfs entries leakage")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Alexander Wetzel <Alexander@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240320213032.18221-1-Alexander@xxxxxxxxxxxxxx
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 86210e4dd0d35..ff6894ce5404e 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -2207,6 +2207,7 @@ sg_remove_sfp_usercontext(struct work_struct *work)
{
struct sg_fd *sfp = container_of(work, struct sg_fd, ew.work);
struct sg_device *sdp = sfp->parentdp;
+ struct scsi_device *device = sdp->device;
Sg_request *srp;
unsigned long iflags;
@@ -2232,8 +2233,9 @@ sg_remove_sfp_usercontext(struct work_struct *work)
"sg_remove_sfp: sfp=0x%p\n", sfp));
kfree(sfp);
- scsi_device_put(sdp->device);
+ WARN_ON_ONCE(kref_read(&sdp->d_ref) != 1);
kref_put(&sdp->d_ref, sg_device_destroy);
+ scsi_device_put(device);
module_put(THIS_MODULE);
}
