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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <3c4608bc-9c84-d79b-de76-b1a1a2a4fb6d@gmail.com>
Date:   Tue, 17 Dec 2019 20:56:53 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     akpm@...ux-foundation.org, ishkamiel@...il.com,
        rostedt@...dmis.org, dvyukov@...gle.com,
        andrea.parri@...rulasolutions.com, anders.roxell@...aro.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        elena.reshetova@...el.com, andreyknvl@...gle.com
Cc:     linux-kernel@...r.kernel.org
Subject: [BUG] kernel: kcov: a possible sleep-in-atomic-context bug in
 kcov_ioctl()

The kernel may sleep while holding a spinlock.
The function call path (from bottom to top) in Linux 4.19 is:

kernel/kcov.c, 237:
     vfree in kcov_put
kernel/kcov.c, 413:
     kcov_put in kcov_ioctl_locked
kernel/kcov.c, 427:
     kcov_ioctl_locked in kcov_ioctl
kernel/kcov.c, 426:
     spin_lock in kcov_ioctl

vfree() can sleep at runtime.

I am not sure how to properly fix this possible bug, so I only report it.
A possible way is to replace vfree() with kfree(), and replace related 
calls to vmalloc() with kmalloc().

This bug is found by a static analysis tool STCheck written by myself.

Best wishes,
Jia-Ju Bai