linux-kernel - Re: [PATCH AUTOSEL 4.14 3/6] drm/crtc: Fix uninit-value bug in drm_mode

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Message-ID: <ZaSlgTAz7vdk97JJ@sashalap>
Date: Sun, 14 Jan 2024 22:24:49 -0500
From: Sasha Levin <sashal@...nel.org>
To: Jani Nikula <jani.nikula@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	tzimmermann@...e.de, Ziqi Zhao <astrajoan@...oo.com>,
	Maxime Ripard <mripard@...nel.org>, dri-devel@...ts.freedesktop.org,
	Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>,
	syzbot+4fad2e57beb6397ab2fc@...kaller.appspotmail.com
Subject: Re: [PATCH AUTOSEL 4.14 3/6] drm/crtc: Fix uninit-value bug in
 drm_mode_setcrtc

On Tue, Dec 19, 2023 at 10:44:02AM +0200, Jani Nikula wrote:
>On Mon, 18 Dec 2023, Sasha Levin <sashal@...nel.org> wrote:
>> From: Ziqi Zhao <astrajoan@...oo.com>
>>
>> [ Upstream commit 3823119b9c2b5f9e9b760336f75bc989b805cde6 ]
>>
>> The connector_set contains uninitialized values when allocated with
>> kmalloc_array. However, in the "out" branch, the logic assumes that any
>> element in connector_set would be equal to NULL if failed to
>> initialize, which causes the bug reported by Syzbot. The fix is to use
>> an extra variable to keep track of how many connectors are initialized
>> indeed, and use that variable to decrease any refcounts in the "out"
>> branch.
>>
>> Reported-by: syzbot+4fad2e57beb6397ab2fc@...kaller.appspotmail.com
>> Signed-off-by: Ziqi Zhao <astrajoan@...oo.com>
>> Reported-and-tested-by: syzbot+4fad2e57beb6397ab2fc@...kaller.appspotmail.com
>> Tested-by: Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
>> Link: https://lore.kernel.org/r/20230721161446.8602-1-astrajoan@yahoo.com
>> Signed-off-by: Maxime Ripard <mripard@...nel.org>
>> Signed-off-by: Sasha Levin <sashal@...nel.org>
>
>This commit fixes an uninitialized value, but introduces a new
>one. Please backport 6e455f5dcdd1 ("drm/crtc: fix uninitialized variable
>use") from v6.7-rc6 to go with it.

I'll take 6e455f5dcdd1 too, thanks!

-- 
Thanks,
Sasha