[U-Boot] [PATCH v2 1/4] disk: efi: Fix memory leak on 'gpt guid'

[Eugeniu Rosca]

Below is what happens on R-Car H3ULCB-KF using clean U-Boot
v2019.04-00810-g6aebc0d11a10 and r8a7795_ulcb_defconfig:

 => ### interrupt autoboot
 => gpt guid mmc 1
 21200400-0804-0146-9dcc-a8c51255994f
 success!
 => ### keep calling 'gpt guid mmc 1'
 => ### on 59th call, we are out of memory:
 => gpt guid mmc 1
 alloc_read_gpt_entries: ERROR: Can't allocate 0X4000 bytes for GPT Entries
 GPT: Failed to allocate memory for PTE
 get_disk_guid: *** ERROR: Invalid GPT ***
 alloc_read_gpt_entries: ERROR: Can't allocate 0X4000 bytes for GPT Entries
 GPT: Failed to allocate memory for PTE
 get_disk_guid: *** ERROR: Invalid Backup GPT ***
 error!

After some inspection, it looks like get_disk_guid(), added via v2017.09
commit 73d6d18b7147c9 ("GPT: add accessor function for disk GUID"),
unlike other callers of is_gpt_valid(), doesn't free the memory pointed
out by 'gpt_entry *gpt_pte'. The latter is allocated by is_gpt_valid()
via alloc_read_gpt_entries().

With the fix applied, the reproduction scenario has been run hundreds
of times ('while true; do gpt guid mmc 1; done') w/o running into OOM.

Fixes: 73d6d18b7147c9 ("GPT: add accessor function for disk GUID")
Signed-off-by: Eugeniu Rosca <erosca at de.adit-jv.com>
Reviewed-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
--
v2:
 - Added Reviewed-by: Heinrich Schuchardt
v1:
 - https://patchwork.ozlabs.org/patch/1092942/
---
 disk/part_efi.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/disk/part_efi.c b/disk/part_efi.c
index 239455b8161e..812d14cdd871 100644
--- a/disk/part_efi.c
+++ b/disk/part_efi.c
@@ -209,6 +209,8 @@ int get_disk_guid(struct blk_desc * dev_desc, char *guid)
 	guid_bin = gpt_head->disk_guid.b;
 	uuid_bin_to_str(guid_bin, guid, UUID_STR_FORMAT_GUID);
 
+	/* Remember to free pte */
+	free(gpt_pte);
 	return 0;
 }
 
-- 
2.21.0