On 11 December 2016 at 07:46, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: > Hello, > > I am getting the following use-after-free reports while running > syzkaller fuzzer. > On commit 318c8932ddec5c1c26a4af0f3c053784841c598e (Dec 7). > Unfortunately it is not reproducible, but all reports look sane and > very similar, so I would assume that it is some hard to trigger race. > In all cases the use-after-free offset within struct kvm is 344 bytes. > This points to srcu field, which starts at 208 with size 360 (I have > some debug configs enabled). [...] > [ 376.024345] [<ffffffff81a77f7e>] __fput+0x34e/0x910 fs/file_table.c:208 > [ 376.024345] [<ffffffff81a785ca>] ____fput+0x1a/0x20 fs/file_table.c:244 I've been hitting what I think is a struct file refcounting bug which causes similar symptoms as you have here (the struct file is freed while somebody still has an active reference to it). > [ 376.024345] [<ffffffff81483c20>] task_work_run+0x1a0/0x280 > kernel/task_work.c:116 > [ 376.024345] [< inline >] exit_task_work include/linux/task_work.h:21 > [ 376.024345] [<ffffffff814129e2>] do_exit+0x1842/0x2650 kernel/exit.c:828 > [ 376.024345] [<ffffffff814139ae>] do_group_exit+0x14e/0x420 kernel/exit.c:932 > [ 376.024345] [<ffffffff81442b43>] get_signal+0x663/0x1880 > kernel/signal.c:2307 > [ 376.024345] [<ffffffff81239b45>] do_signal+0xc5/0x2190 > arch/x86/kernel/signal.c:807 Was this or any other process by any chance killed by the OOM killer? That seems to be a pattern in the crashes I've seen. If not, do you know what killed this process? Vegard -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
