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From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Linus Walleij <linus.walleij@linaro.org>,
	kasan-dev <kasan-dev@googlegroups.com>,
	syzkaller <syzkaller@googlegroups.com>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Hailong Liu <liu.hailong6@zte.com.cn>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: Arm + KASAN + syzbot
Date: Tue, 19 Jan 2021 10:55:17 +0000	[thread overview]
Message-ID: <20210119105517.GG1551@shell.armlinux.org.uk> (raw)
In-Reply-To: <CACT4Y+aPPz-gf2VyZ6cXLeeajLyrWQi66xyr2aA8ZCS1ZruTSg@mail.gmail.com>

On Tue, Jan 19, 2021 at 11:34:33AM +0100, Dmitry Vyukov wrote:
> My first guess would be is that current itself if NULL. Accesses to
> current->kcov* are well tested on other arches, including using KCOV
> in interrupts, etc.

There is a window in dup_task_struct() where the new thread info has
a NULL ->task pointer, but this will never be the current thread,
and so would not affect current.

If we do have a NULL current, that would cause the kernel to explode,
since a context switch to or from such a case would dereference a NULL
pointer.

So, I think your theory is highly unlikely.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

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  reply	other threads:[~2021-01-19 10:56 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-18 16:31 Arm + KASAN + syzbot Dmitry Vyukov
2021-01-19  8:36 ` Krzysztof Kozlowski
2021-01-19  8:46   ` Linus Walleij
2021-01-19 10:04   ` Dmitry Vyukov
2021-01-19 10:17     ` Linus Walleij
2021-01-19 10:23       ` Dmitry Vyukov
2021-01-19 10:28         ` Linus Walleij
2021-01-19 10:53           ` Dmitry Vyukov
2021-01-19 11:05             ` Dmitry Vyukov
2021-01-19 11:13               ` Russell King - ARM Linux admin
2021-01-19 11:17                 ` Dmitry Vyukov
2021-01-19 11:43                   ` Russell King - ARM Linux admin
2021-01-19 12:05                     ` Dmitry Vyukov
2021-01-19 12:36                       ` Russell King - ARM Linux admin
2021-01-19 18:57                         ` Dmitry Vyukov
2021-01-19 19:48                           ` Russell King - ARM Linux admin
2021-01-21 13:14                             ` Russell King - ARM Linux admin
2021-01-21 13:49                               ` Dmitry Vyukov
2021-01-21 14:04                                 ` Arnd Bergmann
2021-01-21 13:59                             ` Dmitry Vyukov
2021-01-21 14:52                               ` Linus Walleij
2021-01-26 21:24                                 ` Dmitry Vyukov
2021-01-27  8:24                                   ` Linus Walleij
2021-01-27  9:39                                     ` Dmitry Vyukov
2021-01-27  9:57                                       ` Linus Walleij
2021-01-27 10:12                                         ` Dmitry Vyukov
2021-01-27 10:19                                     ` Russell King - ARM Linux admin
2021-03-11 10:54                                       ` Dmitry Vyukov
2021-03-11 13:42                                         ` Russell King - ARM Linux admin
2021-03-11 18:05                                           ` Dmitry Vyukov
2021-03-11 13:55                                         ` Linus Walleij
2021-03-11 14:09                                           ` Russell King - ARM Linux admin
2021-03-11 14:37                                             ` Linus Walleij
2021-03-11 14:55                                             ` Arnd Bergmann
2021-03-11 18:08                                               ` Dmitry Vyukov
2021-03-15 14:01                                               ` Linus Walleij
2021-03-15 19:03                                                 ` Russell King - ARM Linux admin
2021-01-19 13:22                       ` Linus Walleij
2021-01-19  8:41 ` Linus Walleij
2021-01-19  8:43   ` Linus Walleij
2021-01-19 10:18   ` Dmitry Vyukov
2021-01-19 10:27     ` Linus Walleij
2021-01-19 10:36       ` Dmitry Vyukov
2021-01-19 10:03 ` Mark Rutland
2021-01-19 10:34   ` Dmitry Vyukov
2021-01-19 10:55     ` Russell King - ARM Linux admin [this message]
2021-01-19 13:00     ` Mark Rutland

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