[Xen-changelog] [xen master] x86: fix bug_line()

[patchbot@xxxxxxx]

commit 48830988a28b7fb1eed225354e25572aa955749a
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Mon Oct 14 08:52:18 2013 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Oct 14 08:52:18 2013 +0200

    x86: fix bug_line()
    
    Due to the packing into a bit field together with a relocated field,
    the computation can overflow when the relocated field ends up getting a
    negative value stored. Hence it isn't sufficient to correct the value
    by 1 in this case, but we also need to mask the result to the width of
    the original bit field.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Keir Fraser <keir@xxxxxxx>
---
 xen/include/asm-x86/bug.h |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/xen/include/asm-x86/bug.h b/xen/include/asm-x86/bug.h
index 956bfd2..cd862e3 100644
--- a/xen/include/asm-x86/bug.h
+++ b/xen/include/asm-x86/bug.h
@@ -15,9 +15,11 @@ struct bug_frame {
 
 #define bug_loc(b) ((const void *)(b) + (b)->loc_disp)
 #define bug_ptr(b) ((const void *)(b) + (b)->ptr_disp)
-#define bug_line(b) ((((b)->line_hi + ((b)->loc_disp < 0)) <<                \
+#define bug_line(b) (((((b)->line_hi + ((b)->loc_disp < 0)) &                \
+                       ((1 << BUG_LINE_HI_WIDTH) - 1)) <<                    \
                       BUG_LINE_LO_WIDTH) +                                   \
-                     (b)->line_lo + ((b)->ptr_disp < 0))
+                     (((b)->line_lo + ((b)->ptr_disp < 0)) &                 \
+                      ((1 << BUG_LINE_LO_WIDTH) - 1)))
 #define bug_msg(b) ((const char *)(b) + (b)->msg_disp[1])
 
 #define BUGFRAME_run_fn 0
--
generated by git-patchbot for /home/xen/git/xen.git#master

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