Messages in this thread | | | From | "Zhang, Qiang1" <> | Subject | RE: [syzbot] KASAN: use-after-free Read in dev_uevent | Date | Wed, 23 Feb 2022 08:08:52 +0000 |
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On Wed, Feb 23, 2022 at 06:51:10AM +0000, Zhang, Qiang1 wrote: > > HEAD commit: 4f12b742eb2b Merge tag 'nfs-for-5.17-3' of git://git.linux.. > git tree: upstream > console output: > https://syzkaller.appspot.com/x/log.txt?x=110a6df2700000 > kernel config: > https://syzkaller.appspot.com/x/.config?x=f6a069ed94a1ed1d > dashboard link: https://syzkaller.appspot.com/bug?extid=348b571beb5eeb70a582 > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12377296700000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+348b571beb5eeb70a582@syzkaller.appspotmail.com > > ================================================================== > BUG: KASAN: use-after-free in dev_uevent+0x712/0x780 > drivers/base/core.c:2320 Read of size 8 at addr ffff88802b934098 by > task udevd/3689 > > CPU: 2 PID: 3689 Comm: udevd Not tainted 5.17.0-rc4-syzkaller-00229-g4f12b742eb2b #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 > print_address_description.constprop.0.cold+0x8d/0x303 > mm/kasan/report.c:255 __kasan_report mm/kasan/report.c:442 [inline] > kasan_report.cold+0x83/0xdf mm/kasan/report.c:459 > dev_uevent+0x712/0x780 drivers/base/core.c:2320 > uevent_show+0x1b8/0x380 drivers/base/core.c:2391 > dev_attr_show+0x4b/0x90 drivers/base/core.c:2094 > sysfs_kf_seq_show+0x219/0x3d0 fs/sysfs/file.c:59 > seq_read_iter+0x4f5/0x1280 fs/seq_file.c:230 > kernfs_fop_read_iter+0x514/0x6f0 fs/kernfs/file.c:241 call_read_iter > include/linux/fs.h:2068 [inline] > new_sync_read+0x429/0x6e0 fs/read_write.c:400 > vfs_read+0x35c/0x600 fs/read_write.c:481 > ksys_read+0x12d/0x250 fs/read_write.c:619 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x44/0xae > RIP: 0033:0x7f964cc558fe > Code: c0 e9 e6 fe ff ff 50 48 8d 3d 0e c7 09 00 e8 c9 cf 01 00 66 0f > 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d > 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28 > RSP: 002b:00007ffc0133d258 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 > RAX: ffffffffffffffda RBX: 000056497b21a140 RCX: 00007f964cc558fe > RDX: 0000000000001000 RSI: 000056497b218650 RDI: 0000000000000008 > RBP: 00007f964cd22380 R08: 0000000000000008 R09: 00007f964cd25a60 > R10: 0000000000000008 R11: 0000000000000246 R12: 000056497b21a140 > R13: 0000000000000d68 R14: 00007f964cd21780 R15: 0000000000000d68 > </TASK> > > > Hi All > > This should be because when the raw_dev is released, the 'driver' > address has expired, although the usb_gadget_remove_driver() empty 'dev.driver ' NULL, but UAF cannot be avoided. > > static int dev_uevent(struct kobject *kobj, struct kobj_uevent_env > *env) { ..... > if (dev->driver) > 2320 add_uevent_var(env, "DRIVER=%s", dev->driver->name); > ..... > } > > Whether protection can be added when operating 'dev->driver'? > >When the driver structure is unbound, this should be set to NULL. Why isn't that happening?
Yes, it should be set NULL at:
close raw_release ->usb_gadget_unregister_driver -> usb_gadget_remove_driver { ...... udc->driver = NULL; udc->dev.driver = NULL; udc->gadget->dev.driver = NULL; }
kref_put(&dev->count, dev_free) -> dev_free kfree(dev) <------------------------------------------ raw_dev be freed
if the udev process not meet it. The UAF maybe can trigger. Did I miss something?
thanks, Zqiang
> >thanks, > >greg k-h
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