[PATCH] bootstd: Avoid freeing a non-allocated buffer

[Shantur Rathore]

On Thu, Nov 16, 2023 at 1:35 AM Simon Glass <sjg at chromium.org> wrote:
>
> EFI applications can be very large and thus used to cause boot failures
> when malloc() space was exhausted.
>
> A recent changed fixed this by using the kernel_addr_r environment var
> as the address of the buffer. However, it still frees the buffer when
> the bootflow is discarded.
>
> Fix this by introducing a flag to indicate whether the buffer was
> allocated, or not.
>
> Note that kernel_addr_r is not the last word here. It might be better
> to use lmb to place images. But there is a lot of refactoring to do
> before we can remove the environment variables. The distro scripts rely
> on them so it is safe for bootstd to do so too.
>
> Fixes: 6a8c2f9781c bootstd: Avoid allocating memory for the EFI file
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> Reported by: Simon Glass <sjg at chromium.org>
> Reported by: Shantur Rathore <i at shantur.com>
Tested-by: Shantur Rathore <i at shantur.com>
> ---
>
>  boot/bootflow.c     | 3 ++-
>  boot/bootmeth_efi.c | 1 +
>  include/bootflow.h  | 5 ++++-
>  3 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/boot/bootflow.c b/boot/bootflow.c
> index 6922e7e0c4e7..1ea2966ae9a5 100644
> --- a/boot/bootflow.c
> +++ b/boot/bootflow.c
> @@ -467,7 +467,8 @@ void bootflow_free(struct bootflow *bflow)
>         free(bflow->name);
>         free(bflow->subdir);
>         free(bflow->fname);
> -       free(bflow->buf);
> +       if (!(bflow->flags & BOOTFLOWF_STATIC_BUF))
> +               free(bflow->buf);
>         free(bflow->os_name);
>         free(bflow->fdt_fname);
>         free(bflow->bootmeth_priv);
> diff --git a/boot/bootmeth_efi.c b/boot/bootmeth_efi.c
> index ae936c8daa18..9ba7734911e1 100644
> --- a/boot/bootmeth_efi.c
> +++ b/boot/bootmeth_efi.c
> @@ -160,6 +160,7 @@ static int efiload_read_file(struct bootflow *bflow, ulong addr)
>         if (ret)
>                 return log_msg_ret("read", ret);
>         bflow->buf = map_sysmem(addr, bflow->size);
> +       bflow->flags |= BOOTFLOWF_STATIC_BUF;
>
>         set_efi_bootdev(desc, bflow);
>
> diff --git a/include/bootflow.h b/include/bootflow.h
> index 44d3741eacae..fede8f22a2b8 100644
> --- a/include/bootflow.h
> +++ b/include/bootflow.h
> @@ -43,9 +43,12 @@ enum bootflow_state_t {
>   *     and it is using the prior-stage FDT, which is the U-Boot control FDT.
>   *     This is only possible with the EFI bootmeth (distro-efi) and only when
>   *     CONFIG_OF_HAS_PRIOR_STAGE is enabled
> + * @BOOTFLOWF_STATIC_BUF: Indicates that @bflow->buf is statically set, rather
> + *     than being allocated by malloc().
>   */
>  enum bootflow_flags_t {
>         BOOTFLOWF_USE_PRIOR_FDT = 1 << 0,
> +       BOOTFLOWF_STATIC_BUF    = 1 << 1,
>  };
>
>  /**
> @@ -72,7 +75,7 @@ enum bootflow_flags_t {
>   * @fname: Filename of bootflow file (allocated)
>   * @logo: Logo to display for this bootflow (BMP format)
>   * @logo_size: Size of the logo in bytes
> - * @buf: Bootflow file contents (allocated)
> + * @buf: Bootflow file contents (allocated unless @flags & BOOTFLOWF_STATIC_BUF)
>   * @size: Size of bootflow file in bytes
>   * @err: Error number received (0 if OK)
>   * @os_name: Name of the OS / distro being booted, or NULL if not known
> --
> 2.43.0.rc0.421.g78406f8d94-goog
>