[Xen-devel] [PATCH] EFI: Fix getting EFI variable list on some systems

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

Copy the entire output buffer to the guest because it may contain data beyond
the output size that the firmware requires on a subsequent
GetNextVariableName() call (e.g. a NULL character).

The spec requires that on each call, "the previous results" be passed in.

Without this change, the following (simplified) sequence would occur:
GetNextVariableName: in \0, out AdminPw\0, size 7
GetNextVariableName: in AdminPw\0, out UserPw\0, size 6
GetNextVariableName: in UserPww\0, NOT FOUND

Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
---
 xen/common/efi/runtime.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/common/efi/runtime.c b/xen/common/efi/runtime.c
index 7ed5bfa..20772f3 100644
--- a/xen/common/efi/runtime.c
+++ b/xen/common/efi/runtime.c
@@ -518,7 +518,7 @@ int efi_runtime_call(struct xenpf_efi_runtime_call *op)
 
             if ( !EFI_ERROR(status) &&
                  copy_to_guest(op->u.get_next_variable_name.name,
-                               name.raw, size) )
+                               name.raw, op->u.get_next_variable_name.size) )
                 rc = -EFAULT;
             op->u.get_next_variable_name.size = size;
         }
-- 
2.1.0


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