linux-kernel - Possible race in ucb1400

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: <237b7e86-f8da-ae37-b56d-4786bbfaefc4@ispras.ru>
Date:   Tue, 15 Aug 2017 16:46:25 +0300
From:   Anton Volkov <avolkov@...ras.ru>
To:     marek.vasut@...il.com, dmitry.torokhov@...il.com
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        ldv-project@...uxtesting.org,
        Alexey Khoroshilov <khoroshilov@...ras.ru>
Subject: Possible race in ucb1400_ts.ko

Hello.

While searching for races in the Linux kernel I've come across 
"drivers/input/touchscreen/ucb1400_ts.ko" module. Here is a question 
that I came up with while analyzing results. Lines are given using the 
info from Linux v4.12.

Consider the following case:

Thread 1:                   Thread 2:
ucb1400_suspend
->ucb1400_ts_start
     ucb->stopped = false
     enable_irq()

ucb1400_resume
->ucb1400_ts_stop           ucb1400_irq
     ucb->stopped = true       while(!ucb->stopped && ...)
     (ucb1400_ts.c: line 230)  (ucb1400_ts.c: line 202)
     disable_irq()

The value of ucb->stopped may be changed in the midst of 'while' loop 
iterations or prevent all of them from happening. Is this feasible from 
your point of view? If so, is it a benign race or is it serious?

Thank you for your time.

-- Anton Volkov
Linux Verification Center, ISPRAS
web: http://linuxtesting.org
e-mail: avolkov@...ras.ru