Re: [syzbot] [usb?] KASAN: slab-use-after-free Read in stub_rx_loop

[Hillf Danton]

> Date: Wed, 26 Aug 2026 09:49:36 -0700	[thread overview]
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    818bebeb63dd drm/xe: Don't hand out the flat CCS storage a..
> git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> console output: https://syzkaller.appspot.com/x/log.txt?x=151ce979580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=ccca94d2c01b9e78
> dashboard link: https://syzkaller.appspot.com/bug?extid=06fa667a0931a3430026
> compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13a28d49580000

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 818bebeb63dd

syzbot reported a uaf in stub_rx_loop(), so see if it happened after the
complete callback.

Reported-by: syzbot+06fa667a0931a3430026@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Hillf Danton <hdanton@xxxxxxxx>
---
 drivers/usb/usbip/stub_rx.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/usbip/stub_rx.c b/drivers/usb/usbip/stub_rx.c
index 1e9ae57..26233ca 100644
--- a/drivers/usb/usbip/stub_rx.c
+++ b/drivers/usb/usbip/stub_rx.c
@@ -606,7 +606,8 @@ static void stub_recv_cmd_submit(struct stub_device *sdev,
 		return;
 
 	/* urb is now ready to submit */
-	for (i = 0; i < priv->num_urbs; i++) {
+	num_urbs = priv->num_urbs;
+	for (i = 0; i < num_urbs; i++) {
 		if (!is_tweaked) {
 			ret = usb_submit_urb(priv->urbs[i], GFP_KERNEL);
 
--