[Xen-changelog] [xen master] EFI: fix getting EFI variable list on some systems

[patchbot@xxxxxxx]

commit 1f4eb9d27d0ebd62a0b6cdff8213726f5ae8f25c
Author:     Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
AuthorDate: Tue Mar 10 13:52:01 2015 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Mar 10 13:52:01 2015 +0100

    EFI: fix getting EFI variable list on some systems
    
    Copy the entire output buffer to the guest because some firmwares update
    size on successful calls (contrary to the spec) and the buffer may
    contain data beyond the output size that the firmware requires on a
    subsequent GetNextVariableName() call (e.g. a NULL character).
    
    Note that this shouldn't change the amount of data copied because on 
success, a
    compliant firmware does not change size and so the entire buffer is copied
    anyway.  If size is changed, Xen does not copy the buffer.
    
    Without this change, the following (simplified) sequence would occur:
    GetNextVariableName: in \0, size 1024 || out AdminPw\0, size 7
    GetNextVariableName: in AdminPw\0, size 1024 || out UserPw\0, size 6
    GetNextVariableName: in UserPww\0, size 1024 || NOT FOUND
    
    This was seen on an Intel S1200RP_SE with firmware
    S1200RP.86B.02.02.0005.102320140911, version 4.6, date 2014-10-23.
    
    Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/common/efi/runtime.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/xen/common/efi/runtime.c b/xen/common/efi/runtime.c
index 7ed5bfa..5ed8b01 100644
--- a/xen/common/efi/runtime.c
+++ b/xen/common/efi/runtime.c
@@ -516,9 +516,13 @@ int efi_runtime_call(struct xenpf_efi_runtime_call *op)
                 cast_guid(&op->u.get_next_variable_name.vendor_guid));
             efi_rs_leave(cr3);
 
+            /*
+             * Copy the variable name if necessary. The caller provided size
+             * is used because some firmwares update size when they shouldn't.
+             * */
             if ( !EFI_ERROR(status) &&
-                 copy_to_guest(op->u.get_next_variable_name.name,
-                               name.raw, size) )
+                 __copy_to_guest(op->u.get_next_variable_name.name,
+                                 name.raw, op->u.get_next_variable_name.size) )
                 rc = -EFAULT;
             op->u.get_next_variable_name.size = size;
         }
--
generated by git-patchbot for /home/xen/git/xen.git#master

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog