Commit 27f58c04 authored by Alexander Wetzel's avatar Alexander Wetzel Committed by Martin K. Petersen
Browse files

scsi: sg: Avoid sg device teardown race 

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@wetzel-home.de


Fixes: db59133e ("scsi: sg: fix blktrace debugfs entries leakage")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarAlexander Wetzel <Alexander@wetzel-home.de>
Link: https://lore.kernel.org/r/20240320213032.18221-1-Alexander@wetzel-home.de


Reviewed-by: default avatarBart Van Assche <bvanassche@acm.org>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent f02fe780

drivers/scsi/sg.c

+3 −1
Original line number Diff line number Diff line
@@ -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);

}