x86/efi: Fix dummy variable buffer allocation

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>

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 0017a15c98c42583ee50a5aa042bb5799cf708f6..46e5387f57823e747080cee4a91adaaaa5109a0b 100644 (file)
--- 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(u32 attributes, unsigned long size)
                 * 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(u32 attributes, unsigned long size)
                                         0, dummy);
                }
 
+               kfree(dummy);
+
                /*
                 * The runtime code may now have triggered a garbage collection
                 * run, so check the variable info again