[U-Boot] [PATCH 2/3] efi: add protection for block_dev

[Patrick Delaunay <patrick.delaunay@st.com>]

Check the value of block_dev before to use this pointer.

This patch solves problem for the command "load" when ubifs
is previously mounted: in this case the function
blk_get_device_part_str("ubi 0") don't return error but return
block_dev = NULL and then data abort.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
---

To reproduce the issue, I have a boot script 'boot.scr.uimg'
with a load command executed during ubi boot:

load ${devtype} ${devnum}:${distro_bootpart} ${m4fw_addr} ${m4fw_name}

I have a data abort for call stack:
- do_load_wrapper for "ubi 0"
-- efi_set_bootdev
--- efi_dp_from_name

=> desc = 0 and data abort for access to 'desc->*'

I also proposed a protection for the same issue in ums command
http://patchwork.ozlabs.org/project/uboot/list/?series=68096


 lib/efi_loader/efi_device_path.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c
index 53b40c8..fd57be8 100644
--- a/lib/efi_loader/efi_device_path.c
+++ b/lib/efi_loader/efi_device_path.c
@@ -970,7 +970,7 @@ efi_status_t efi_dp_from_name(const char *dev, const char *devnr,
 	if (!is_net) {
 		part = blk_get_device_part_str(dev, devnr, &desc, &fs_partition,
 					       1);
-		if (part < 0)
+		if (part < 0 || !desc)
 			return EFI_INVALID_PARAMETER;
 
 		if (device)
-- 
2.7.4