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Message-ID: <YfPCxX/iiDWUpWjY@kroah.com>
Date: Fri, 28 Jan 2022 11:17:41 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Zhou Qingyang <zhou1615@....edu>
Cc: kjlu@....edu, Harry Wentland <harry.wentland@....com>,
Leo Li <sunpeng.li@....com>,
Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
Alex Deucher <alexander.deucher@....com>,
Christian König <christian.koenig@....com>,
"Pan, Xinhui" <Xinhui.Pan@....com>,
David Airlie <airlied@...ux.ie>,
Daniel Vetter <daniel@...ll.ch>,
Lee Jones <lee.jones@...aro.org>,
Mario Kleiner <mario.kleiner.de@...il.com>,
amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/amd/display/dc/calcs/dce_calcs: Fix a memleak in
calculate_bandwidth()
On Tue, Jan 25, 2022 at 12:55:51AM +0800, Zhou Qingyang wrote:
> In calculate_bandwidth(), the tag free_sclk and free_yclk are reversed,
> which could lead to a memory leak of yclk.
>
> Fix this bug by changing the location of free_sclk and free_yclk.
>
> This bug was found by a static analyzer.
>
> Builds with 'make allyesconfig' show no new warnings,
> and our static analyzer no longer warns about this code.
>
> Fixes: 2be8989d0fc2 ("drm/amd/display/dc/calcs/dce_calcs: Move some large variables from the stack to the heap")
> Signed-off-by: Zhou Qingyang <zhou1615@....edu>
> ---
> The analysis employs differential checking to identify inconsistent
> security operations (e.g., checks or kfrees) between two code paths
> and confirms that the inconsistent operations are not recovered in the
> current function or the callers, so they constitute bugs.
>
> Note that, as a bug found by static analysis, it can be a false
> positive or hard to trigger. Multiple researchers have cross-reviewed
> the bug.
>
> drivers/gpu/drm/amd/display/dc/calcs/dce_calcs.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/calcs/dce_calcs.c b/drivers/gpu/drm/amd/display/dc/calcs/dce_calcs.c
> index ff5bb152ef49..e6ef36de0825 100644
> --- a/drivers/gpu/drm/amd/display/dc/calcs/dce_calcs.c
> +++ b/drivers/gpu/drm/amd/display/dc/calcs/dce_calcs.c
> @@ -2033,10 +2033,10 @@ static void calculate_bandwidth(
> kfree(surface_type);
> free_tiling_mode:
> kfree(tiling_mode);
> -free_yclk:
> - kfree(yclk);
> free_sclk:
> kfree(sclk);
> +free_yclk:
> + kfree(yclk);
> }
>
> /*******************************************************************************
> --
> 2.25.1
>
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Linux kernel. Please work with your administration to resolve this
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