[Xen-devel] [PATCH 1/2] efi/boot: fix set_color function

[Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>]

- 0 is a possible and allowed value for a color mask accroding to
  UEFI Spec 2.6 (11.9) especially for reserved mask
- add missing pointer dereference

Without these changes non-TrueColor modes won't work which will cause
GOP init to fail - observed while trying to boot EFI Xen with Cirrus VGA.

Signed-off-by: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
---
 xen/common/efi/boot.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index 9a89414..933db88 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -1113,10 +1113,14 @@ static int __init __maybe_unused set_color(u32 mask, 
int bpp, u8 *pos, u8 *sz)
    if ( bpp < 0 )
        return bpp;
    if ( !mask )
-       return -EINVAL;
+   {
+       *pos = 0;
+       *sz = 0;
+       return bpp;
+   }
    for ( *pos = 0; !(mask & 1); ++*pos )
        mask >>= 1;
-   for ( *sz = 0; mask & 1; ++sz)
+   for ( *sz = 0; mask & 1; ++*sz)
        mask >>= 1;
    if ( mask )
        return -EINVAL;
-- 
2.7.4


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