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> --- Changes compared to V2: - Fixed the use-after-free pointed out by Bart - Added the WARN_ON_ONCE() requested by Bart - added the Fixes tag pointed out by Greg This patch has now been tested with KASAN enabled. I also verified, that db59133e9279 ("scsi: sg: fix blktrace debugfs entries leakage") introduced the issue. Thanks for all your help! Alexander --- drivers/scsi/sg.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 86210e4dd0d3..ff6894ce5404 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); } -- 2.44.0
