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Message-ID: <0a48d61b-6e11-9144-b11e-dd46de836c53@embeddedor.com>
Date:   Wed, 22 Mar 2023 15:38:57 -0600
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Subject: Re: [PATCH] drm/nouveau/disp: More DP_RECEIVER_CAP_SIZE array fixes
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To:     Kees Cook <keescook@chromium.org>, Ben Skeggs <bskeggs@redhat.com>
Cc:     Lyude Paul <lyude@redhat.com>, Karol Herbst <kherbst@redhat.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Dave Airlie <airlied@redhat.com>,
        dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
References: <20230204184307.never.825-kees@kernel.org>
From:   "Gustavo A. R. Silva" <gustavo@embeddedor.com>
In-Reply-To: <20230204184307.never.825-kees@kernel.org>
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On 2/4/23 12:43, Kees Cook wrote:
> More arrays (and arguments) for dcpd were set to 16, when it looks like
> DP_RECEIVER_CAP_SIZE (15) should be used. Fix the remaining cases, seen
> with GCC 13:
> 
> ../drivers/gpu/drm/nouveau/nvif/outp.c: In function 'nvif_outp_acquire_dp':
> ../include/linux/fortify-string.h:57:33: warning: array subscript 'unsigned char[16][0]' is partly outside array bounds of 'u8[15]' {aka 'unsigned char[15]'} [-Warray-bounds=]
>     57 | #define __underlying_memcpy     __builtin_memcpy
>        |                                 ^
> ...
> ../drivers/gpu/drm/nouveau/nvif/outp.c:140:9: note: in expansion of macro 'memcpy'
>    140 |         memcpy(args.dp.dpcd, dpcd, sizeof(args.dp.dpcd));
>        |         ^~~~~~
> ../drivers/gpu/drm/nouveau/nvif/outp.c:130:49: note: object 'dpcd' of size [0, 15]
>    130 | nvif_outp_acquire_dp(struct nvif_outp *outp, u8 dpcd[DP_RECEIVER_CAP_SIZE],
>        |                                              ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Fixes: 813443721331 ("drm/nouveau/disp: move DP link config into acquire")
> Cc: Ben Skeggs <bskeggs@redhat.com>
> Cc: Lyude Paul <lyude@redhat.com>
> Cc: Karol Herbst <kherbst@redhat.com>
> Cc: David Airlie <airlied@gmail.com>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: Dave Airlie <airlied@redhat.com>
> Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
> Cc: dri-devel@lists.freedesktop.org
> Cc: nouveau@lists.freedesktop.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks!
--
Gustavo

> ---
>   drivers/gpu/drm/nouveau/include/nvif/if0012.h    | 4 +++-
>   drivers/gpu/drm/nouveau/nvkm/engine/disp/outp.h  | 3 ++-
>   drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c | 2 +-
>   3 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/include/nvif/if0012.h b/drivers/gpu/drm/nouveau/include/nvif/if0012.h
> index eb99d84eb844..16d4ad5023a3 100644
> --- a/drivers/gpu/drm/nouveau/include/nvif/if0012.h
> +++ b/drivers/gpu/drm/nouveau/include/nvif/if0012.h
> @@ -2,6 +2,8 @@
>   #ifndef __NVIF_IF0012_H__
>   #define __NVIF_IF0012_H__
>   
> +#include <drm/display/drm_dp.h>
> +
>   union nvif_outp_args {
>   	struct nvif_outp_v0 {
>   		__u8 version;
> @@ -63,7 +65,7 @@ union nvif_outp_acquire_args {
>   				__u8 hda;
>   				__u8 mst;
>   				__u8 pad04[4];
> -				__u8 dpcd[16];
> +				__u8 dpcd[DP_RECEIVER_CAP_SIZE];
>   			} dp;
>   		};
>   	} v0;
> diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/outp.h b/drivers/gpu/drm/nouveau/nvkm/engine/disp/outp.h
> index b7631c1ab242..4e7f873f66e2 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/outp.h
> +++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/outp.h
> @@ -3,6 +3,7 @@
>   #define __NVKM_DISP_OUTP_H__
>   #include "priv.h"
>   
> +#include <drm/display/drm_dp.h>
>   #include <subdev/bios.h>
>   #include <subdev/bios/dcb.h>
>   #include <subdev/bios/dp.h>
> @@ -42,7 +43,7 @@ struct nvkm_outp {
>   			bool aux_pwr_pu;
>   			u8 lttpr[6];
>   			u8 lttprs;
> -			u8 dpcd[16];
> +			u8 dpcd[DP_RECEIVER_CAP_SIZE];
>   
>   			struct {
>   				int dpcd; /* -1, or index into SUPPORTED_LINK_RATES table */
> diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c
> index 4f0ca709c85a..fc283a4a1522 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c
> @@ -146,7 +146,7 @@ nvkm_uoutp_mthd_release(struct nvkm_outp *outp, void *argv, u32 argc)
>   }
>   
>   static int
> -nvkm_uoutp_mthd_acquire_dp(struct nvkm_outp *outp, u8 dpcd[16],
> +nvkm_uoutp_mthd_acquire_dp(struct nvkm_outp *outp, u8 dpcd[DP_RECEIVER_CAP_SIZE],
>   			   u8 link_nr, u8 link_bw, bool hda, bool mst)
>   {
>   	int ret;