Messages in this thread | | | Subject | Re: [BUG] kernel: kcov: a possible sleep-in-atomic-context bug in kcov_ioctl() | From | Jia-Ju Bai <> | Date | Thu, 21 Jun 2018 11:50:54 +0800 |
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On 2018/6/21 11:43, Al Viro wrote: > On Thu, Jun 21, 2018 at 11:20:59AM +0800, Jia-Ju Bai wrote: >> The kernel may sleep with holding a spinlock. >> The function call path (from bottom to top) in Linux-4.16.7 is: >> >> [FUNC] vfree --> can sleep >> kernel/kcov.c, 237: vfree in kcov_put >> kernel/kcov.c, 396: kcov_put in kcov_ioctl_locked >> kernel/kcov.c, 410: kcov_ioctl_locked in kcov_ioctl >> kernel/kcov.c, 409: spin_lock in kcov_ioctl >> >> This bug is found by my static analysis tool (DSAC-2) and checked by my >> code review. >> >> I do not know how to correctly fix this bug, so I just report them. > Assuming it's a bug in the first place, that is. Note that > * we never modify task->kcov for task != current > * task->kcov contributes to refcount > * opened file contributes to refcount > * that kcov_put() of yours happens from ->ioctl() and removes > current->kcov reference; it *can't* be the last reference - the one > held by struct file used to call ->ioctl() is also there. > > IOW, it's a false positive.
Okay, thanks for your reply and explanation. I agree that my report is false.
Best wishes, Jia-Ju Bai
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