[U-Boot] [PATCH] efi_loader: Exit in efi_set_bootdev() upon invalid "desc"

[Heinrich Schuchardt]

On 11/17/2017 08:47 AM, Stefan Roese wrote:
> When trying to load an image from a non-existent USB key, U-Boot v2017.11
> crashes on my x86 platform:
> 
> => load usb 0:1 03000000 abc
> General Protection
> EIP: 0010:[<7b59030d>] EFLAGS: 00010286
> Original EIP :[<fff4330d>]
> ...
> 
> This used to work in v2017.09. Testing has shown, that this bug was
> introduced with patch 95c5553e [efi_loader: refactor boot device and
> loaded_image handling].
> 
> This patch now checks if a valid "desc" is returned from blk_get_dev()
> and only continues when "desc" is available. Resulting in this cmd
> output (again):
> 
> => load usb 0:1 03000000 abc
> ** Bad device usb 0 **
> 
> Signed-off-by: Stefan Roese <sr at denx.de>
> Cc: Rob Clark <robdclark at gmail.com>
> Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
> Cc: Alexander Graf <agraf at suse.de>
> Cc: Marek Vasut <marex at denx.de>
> Cc: Bin Meng <bmeng.cn at gmail.com>
> ---
>   cmd/bootefi.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/cmd/bootefi.c b/cmd/bootefi.c
> index 478bc116e2..b468a20d82 100644
> --- a/cmd/bootefi.c
> +++ b/cmd/bootefi.c
> @@ -390,6 +390,8 @@ void efi_set_bootdev(const char *dev, const char *devnr, const char *path)
>   		int part;
>   
>   		desc = blk_get_dev(dev, simple_strtol(devnr, NULL, 10));
> +		if (!desc)
> +			return;
>   		part = parse_partnum(devnr);
>   
>   		bootefi_device_path = efi_dp_from_part(desc, part);
> 

blk_get_dev can return NULL. We should abort efi_set_bootdev() when 
receiving this value.

But I could not reproduce your problem on qemu-x86_64.

Reviewed-by: Heinrich Schuchardt <xypron.glpk at gmx.de>