On 9/20/22 10:46, Rondreis wrote: > Hello, > > When fuzzing the Linux kernel driver v6.0-rc6, the following crash was > triggered. > > HEAD commit: 521a547ced6477c54b4b0cc206000406c221b4d6 > git tree: upstream > > kernel config: https://pastebin.com/raw/hekxU61F > console output: https://pastebin.com/raw/73a8RzBY > > Sorry for failing to extract the reproducer. But on other versions of > Linux, I also triggered this crash. > > I would appreciate it if you have any idea how to solve this bug. > sg_release() calls "kref_put(&sfp->f_ref, sg_remove_sfp)" which eventually does "kref_put(&sdp->d_ref, sg_device_destroy)" which does "kfree(sdp)", but sg_release() continues to access sdp afterward. Try the following patch. >From 82ca6785c40eded6229183a53752fc5e43db4a94 Mon Sep 17 00:00:00 2001 From: Tony Battersby <tonyb@xxxxxxxxxxxxxxx> Date: Thu, 22 Sep 2022 11:05:30 -0400 Subject: [PATCH] scsi: sg: fix memory-use-after-free on device removal Fix memory-use-after-free race when closing a sg fd to a removed device. Link: https://lore.kernel.org/linux-scsi/CAB7eexK_jr1LWOO9RWrBF9as7gAS9kpHjrZFRuRrRJF=1H4W6A@xxxxxxxxxxxxxx/ Reported-by: Rondreis <linhaoguo86@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Tony Battersby <tonyb@xxxxxxxxxxxxxxx> --- drivers/scsi/sg.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 340b050ad28d..f44cbe42dba9 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -388,6 +388,7 @@ sg_release(struct inode *inode, struct file *filp) return -ENXIO; SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sdp, "sg_release\n")); + kref_get(&sdp->d_ref); mutex_lock(&sdp->open_rel_lock); scsi_autopm_put_device(sdp->device); kref_put(&sfp->f_ref, sg_remove_sfp); @@ -402,6 +403,7 @@ sg_release(struct inode *inode, struct file *filp) wake_up_interruptible(&sdp->open_wait); } mutex_unlock(&sdp->open_rel_lock); + kref_put(&sdp->d_ref, sg_device_destroy); return 0; } -- 2.25.1
