Messages in this thread | | | Date | Thu, 21 Jun 2018 04:43:36 +0100 | From | Al Viro <> | Subject | Re: [BUG] kernel: kcov: a possible sleep-in-atomic-context bug in kcov_ioctl() |
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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.
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