On Sat, Aug 12, 2023 at 02:51:30AM -0700, syzbot wrote: > syzbot has bisected this issue to: > > commit 9b4feb630e8e9801603f3cab3a36369e3c1cf88d > Author: Christian Brauner <christian.brauner@xxxxxxxxxx> > Date: Fri May 24 09:31:44 2019 +0000 > > arch: wire-up close_range() > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1323329ba80000 > start commit: 89d77f71f493 Merge tag 'riscv-for-linus-6.4-mw1' of git://.. > git tree: upstream > final oops: https://syzkaller.appspot.com/x/report.txt?x=10a3329ba80000 > console output: https://syzkaller.appspot.com/x/log.txt?x=1723329ba80000 > kernel config: https://syzkaller.appspot.com/x/.config?x=d963e7536cbe545e > dashboard link: https://syzkaller.appspot.com/bug?extid=d6b0b0ea0781c14b2ecf > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11471b84280000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10b98e2c280000 > > Reported-by: syzbot+d6b0b0ea0781c14b2ecf@xxxxxxxxxxxxxxxxxxxxxxxxx > Fixes: 9b4feb630e8e ("arch: wire-up close_range()") > > For information about bisection process see: https://goo.gl/tpsmEJ#bisection This attribution is extremely unlikely. The real problem seems to be some sort of race in usbtmc and the core between URBs being added to an anchor, file I/O being stopped, and URBs being killed or scuttled when the file is flushed. The bug is caused by an URB completing after (or while) its anchor is deallocated. Note that __usb_hcd_giveback_urb() removes an URB from its anchor before calling the completion routine, but dereferences the anchor afterward. The anchor could easily be deallocated during that window. Alan Stern
