Messages in this thread | | | From | Lai Jiangshan <> | Date | Fri, 9 Jul 2021 11:59:01 +0800 | Subject | Re: BUG in alloc_workqueue (linux-next) |
| |
Hello, Pavel Thanks for the report.
Huawei (CC-ed) is also dealing with the problem: https://lore.kernel.org/lkml/20210708093136.2195752-1-yangyingliang@huawei.com/t/#u
Could you have a try on the fix, please?
Thanks Lai
On Thu, Jul 8, 2021 at 9:24 PM Pavel Skripkin <paskripkin@gmail.com> wrote:
> > I've spent some time trying to came up with a fix, but I gave > up :( But! I have an idea about what's happening, maybe it will help > somehow... > > > So, all 3 reports have same stack trace: alloc_workqueue() in > loop_configure(). I skimmed through syzbot's log and found, that syzbot injected > failure into alloc_unbound_pwq() in all 3 cases: > > FAULT_INJECTION: forcing a failure. > name failslab, interval 1, probability 0, space 0, times 0 > CPU: 1 PID: 17986 Comm: syz-executor.0 Tainted: G W 5.13.0-next-20210706 #9 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a-rebuilt.opensuse.org 04/01/2014 > Call Trace: > dump_stack_lvl (lib/dump_stack.c:106 (discriminator 4)) > should_fail.cold (lib/fault-inject.c:52 lib/fault-inject.c:146) > should_failslab (mm/slab_common.c:1327) > kmem_cache_alloc_node (mm/slab.h:487 mm/slub.c:2902 mm/slub.c:3017) > ? alloc_unbound_pwq (kernel/workqueue.c:3813) > alloc_unbound_pwq (kernel/workqueue.c:3813) > apply_wqattrs_prepare (kernel/workqueue.c:3963) > apply_workqueue_attrs_locked (kernel/workqueue.c:4041) > alloc_workqueue (kernel/workqueue.c:4078 kernel/workqueue.c:4201 kernel/workqueue.c:4309) > > > So, if alloc_unbound_pwq() fails, apply_wqattrs_prepare() will jump to > this code: > > out_free: > free_workqueue_attrs(tmp_attrs); > free_workqueue_attrs(new_attrs); > apply_wqattrs_cleanup(ctx); <----| > return NULL; | > | > put_pwq_unlocked() -> put_pwq() -> schedule_work(&pwq->unbound_release_work); > > > and apply_wqattrs_cleanup() will schedule pwq_unbound_release_workfn() > [2], but alloc_workqueue() will free workqueue_struct in case of > alloc_unbound_pwq() error [1]. In that case we will get UAF in pwq_unbound_release_workfn() > like in 3rd report. > > > Does written above make some sence? :) > > > > With regards, > Pavel Skripkin
| |