Re: [PATCH 2/2] efi/gop: Fix memory leak in __gop_query32/64

From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Ard Biesheuvel <ardb@kernel.org>, linux-efi <linux-efi@vger.kernel.org>
Subject: Re: [PATCH 2/2] efi/gop: Fix memory leak in __gop_query32/64
Date: Wed, 4 Dec 2019 15:11:09 +0000	[thread overview]
Message-ID: <CAKv+Gu9tckvD=H4nCbHeNNxEwnK3tHMT59zELf=pYokLS4Nb6g@mail.gmail.com> (raw)
In-Reply-To: <20191203214728.19264-2-nivedita@alum.mit.edu>

On Tue, 3 Dec 2019 at 21:47, Arvind Sankar <nivedita@alum.mit.edu> wrote:
>
> gop->query_mode returns info in callee-allocated memory which must be
> freed by the caller.
>
> We don't actually need to call it in order to obtain the info for the
> current graphics mode, which is already there in gop->mode->info, so
> just access it directly.
>
> Also nothing uses the size of the info structure, so remove the
> argument.
>
> Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>

Thanks Arvind

I agree with this patch in principle, but I'd prefer it if we could
get rid of the __gop_queryXX routines altogether, or if we need a
helper, to at least merge them into on, taking gopXX->mode as an input
argument.

> ---
>  drivers/firmware/efi/libstub/gop.c | 48 ++++++++----------------------
>  1 file changed, 12 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/firmware/efi/libstub/gop.c b/drivers/firmware/efi/libstub/gop.c
> index 235a98797105..c8a39cd89b47 100644
> --- a/drivers/firmware/efi/libstub/gop.c
> +++ b/drivers/firmware/efi/libstub/gop.c
> @@ -83,28 +83,17 @@ setup_pixel_info(struct screen_info *si, u32 pixels_per_scan_line,
>         }
>  }
>
> -static efi_status_t
> +static void
>  __gop_query32(efi_system_table_t *sys_table_arg,
>               struct efi_graphics_output_protocol_32 *gop32,
>               struct efi_graphics_output_mode_info **info,
> -             unsigned long *size, u64 *fb_base)
> +             u64 *fb_base)
>  {
>         struct efi_graphics_output_protocol_mode_32 *mode;
> -       efi_graphics_output_protocol_query_mode query_mode;
> -       efi_status_t status;
> -       unsigned long m;
> -
> -       m = gop32->mode;
> -       mode = (struct efi_graphics_output_protocol_mode_32 *)m;
> -       query_mode = (void *)(unsigned long)gop32->query_mode;
> -
> -       status = __efi_call_early(query_mode, (void *)gop32, mode->mode, size,
> -                                 info);
> -       if (status != EFI_SUCCESS)
> -               return status;
>
> +       mode = (void *)(unsigned long)gop32->mode;
> +       *info = (void *)(unsigned long)mode->info;
>         *fb_base = mode->frame_buffer_base;
> -       return status;
>  }
>
>  static efi_status_t
> @@ -145,9 +134,8 @@ setup_gop32(efi_system_table_t *sys_table_arg, struct screen_info *si,
>                 if (status == EFI_SUCCESS)
>                         conout_found = true;
>
> -               status = __gop_query32(sys_table_arg, gop32, &info, &size,
> -                                      &current_fb_base);
> -               if (status == EFI_SUCCESS && (!first_gop || conout_found) &&
> +               __gop_query32(sys_table_arg, gop32, &info, &current_fb_base);
> +               if ((!first_gop || conout_found) &&
>                     info->pixel_format != PIXEL_BLT_ONLY) {
>                         /*
>                          * Systems that use the UEFI Console Splitter may
> @@ -201,28 +189,17 @@ setup_gop32(efi_system_table_t *sys_table_arg, struct screen_info *si,
>         return EFI_SUCCESS;
>  }
>
> -static efi_status_t
> +static void
>  __gop_query64(efi_system_table_t *sys_table_arg,
>               struct efi_graphics_output_protocol_64 *gop64,
>               struct efi_graphics_output_mode_info **info,
> -             unsigned long *size, u64 *fb_base)
> +             u64 *fb_base)
>  {
>         struct efi_graphics_output_protocol_mode_64 *mode;
> -       efi_graphics_output_protocol_query_mode query_mode;
> -       efi_status_t status;
> -       unsigned long m;
> -
> -       m = gop64->mode;
> -       mode = (struct efi_graphics_output_protocol_mode_64 *)m;
> -       query_mode = (void *)(unsigned long)gop64->query_mode;
> -
> -       status = __efi_call_early(query_mode, (void *)gop64, mode->mode, size,
> -                                 info);
> -       if (status != EFI_SUCCESS)
> -               return status;
>
> +       mode = (void *)(unsigned long)gop64->mode;
> +       *info = (void *)(unsigned long)mode->info;
>         *fb_base = mode->frame_buffer_base;
> -       return status;
>  }
>
>  static efi_status_t
> @@ -263,9 +240,8 @@ setup_gop64(efi_system_table_t *sys_table_arg, struct screen_info *si,
>                 if (status == EFI_SUCCESS)
>                         conout_found = true;
>
> -               status = __gop_query64(sys_table_arg, gop64, &info, &size,
> -                                      &current_fb_base);
> -               if (status == EFI_SUCCESS && (!first_gop || conout_found) &&
> +               __gop_query64(sys_table_arg, gop64, &info, &current_fb_base);
> +               if ((!first_gop || conout_found) &&
>                     info->pixel_format != PIXEL_BLT_ONLY) {
>                         /*
>                          * Systems that use the UEFI Console Splitter may
> --
> 2.23.0
>