linux-kernel - [BUG] kernel: kcov: a possible sleep-in-atomic-context bug in kcov

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Date:   Thu, 21 Jun 2018 11:20:59 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     akpm@...ux-foundation.org, dvyukov@...gle.com,
        Greg KH <gregkh@...uxfoundation.org>, tchibo@...gle.com,
        aryabinin@...tuozzo.com
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [BUG] kernel: kcov: a possible sleep-in-atomic-context bug in
 kcov_ioctl()

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.


Best wishes,
Jia-Ju Bai