[PATCH 3.4 155/214] x86/efi: Fix dummy variable buffer allocation

Greg Kroah-Hartman
2014-06-05T04:38:45Z

From: Ben Hutchings <ben@decadent.org.uk>

commit b8cb62f82103083a6e8fa5470bfe634a2c06514d upstream.

1. Check for allocation failure
2. Clear the buffer contents, as they may actually be written to flash
3. Don't leak the buffer

Compile-tested only.

[ Tested successfully on my buggy ASUS machine - Matt ]

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Cc: Rui Xiang <rui.xiang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/platform/efi/efi.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -1020,7 +1020,10 @@ efi_status_t efi_query_variable_store(u3
* that by attempting to use more space than is available.
*/
unsigned long dummy_size = remaining_size + 1024;
- void *dummy = kmalloc(dummy_size, GFP_ATOMIC);
+ void *dummy = kzalloc(dummy_size, GFP_ATOMIC);
+
+ if (!dummy)
+ return EFI_OUT_OF_RESOURCES;

status = efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID,
EFI_VARIABLE_NON_VOLATILE |
@@ -1040,6 +1043,8 @@ efi_status_t efi_query_variable_store(u3
0, dummy);
}

+ kfree(dummy);
+
/*
* The runtime code may now have triggered a garbage collection
* run, so check the variable info again