commit 27f58c04a8f4 ("scsi: sg: Avoid sg device teardown race") introduced an incorrect WARN_ON_ONCE() and missed a sequence where sg_device_destroy() after scsi_device_put() when handling errors.
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.
Drop the incorrect WARN_ON_ONCE() - allowing more than one concurrent access to the sg device - and make sure sg_device_destroy() is not used after scsi_device_put() in the error handling.
Link: https://lore.kernel.org/all/5375B275-D137-4D5F-BE25-6AF8ACAE41EF@linux.ibm.c... Fixes: 27f58c04a8f4 ("scsi: sg: Avoid sg device teardown race") Cc: stable@vger.kernel.org Signed-off-by: Alexander Wetzel Alexander@wetzel-home.de ---
The WARN_ON_ONCE() was kind of stupid to add: We get add reference for each sg_open(). So opening a second session and then closing either one will trigger the warning... Nothing to warn about here.
Alexander --- drivers/scsi/sg.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 386981c6976a..833c9277419b 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -372,8 +372,9 @@ sg_open(struct inode *inode, struct file *filp) error_out: scsi_autopm_put_device(sdp->device); sdp_put: + kref_put(&sdp->d_ref, sg_device_destroy); scsi_device_put(sdp->device); - goto sg_put; + return retval; }
/* Release resources associated with a successful sg_open() @@ -2233,7 +2234,6 @@ sg_remove_sfp_usercontext(struct work_struct *work) "sg_remove_sfp: sfp=0x%p\n", sfp)); kfree(sfp);
- 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);