x86, kexec: fix crashdump panic with CONFIG_KEXEC_JUMP

Tim Starling reported that crashdump will panic with kernel compiled
with CONFIG_KEXEC_JUMP due to null pointer deference in
machine_kexec_32.c: machine_kexec(), when deferencing
kexec_image. Refering to:

http://bugzilla.kernel.org/show_bug.cgi?id=13265

This patch fixes the BUG via replacing global variable reference:
kexec_image in machine_kexec() with local variable reference: image,
which is more appropriate, and will not be null.

Same BUG is in machine_kexec_64.c too, so fixed too in the same way.

[ Impact: fix crash on kexec ]

Reported-by: Tim Starling <tstarling@wikimedia.org>
Signed-off-by: Huang Ying <ying.huang@intel.com>
LKML-Reference: <1241751101.6259.85.camel@yhuang-dev.sh.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

2 files changed, 4 insertions, 4 deletions

diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c
index e7368c1da01..c1c429d0013 100644
--- a/arch/x86/kernel/machine_kexec_32.c
+++ b/arch/x86/kernel/machine_kexec_32.c
@@ -194,7 +194,7 @@ void machine_kexec(struct kimage *image)
                                        unsigned int preserve_context);
 
 #ifdef CONFIG_KEXEC_JUMP
-        if (kexec_image->preserve_context)
+        if (image->preserve_context)
                 save_processor_state();
 #endif
 
@@ -253,7 +253,7 @@ void machine_kexec(struct kimage *image)
                                            image->preserve_context);
 
 #ifdef CONFIG_KEXEC_JUMP
-        if (kexec_image->preserve_context)
+        if (image->preserve_context)
                 restore_processor_state();
 #endif
 
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 89cea4d4467..84c3bf209e9 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -274,7 +274,7 @@ void machine_kexec(struct kimage *image)
         int save_ftrace_enabled;
 
 #ifdef CONFIG_KEXEC_JUMP
-        if (kexec_image->preserve_context)
+        if (image->preserve_context)
                 save_processor_state();
 #endif
 
@@ -333,7 +333,7 @@ void machine_kexec(struct kimage *image)
                                        image->preserve_context);
 
 #ifdef CONFIG_KEXEC_JUMP
-        if (kexec_image->preserve_context)
+        if (image->preserve_context)
                 restore_processor_state();
 #endif