[PATCH] treewide: avoid the ponter addition with NULL pointer

[sz18665958617]

From: "dean.yang_cp" <yangdianq...@yulong.com>

Signed-off-by: dean.yang_cp <yangdianq...@yulong.com>
---
 arch/arc/kernel/unwind.c | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/arch/arc/kernel/unwind.c b/arch/arc/kernel/unwind.c
index 74ad425..47bab67 100644
--- a/arch/arc/kernel/unwind.c
+++ b/arch/arc/kernel/unwind.c
@@ -187,25 +187,26 @@ static void init_unwind_table(struct unwind_table *table, 
const char *name,
                              const void *table_start, unsigned long table_size,
                              const u8 *header_start, unsigned long header_size)
 {
-       const u8 *ptr = header_start + 4;
-       const u8 *end = header_start + header_size;
-
        table->core.pc = (unsigned long)core_start;
        table->core.range = core_size;
        table->init.pc = (unsigned long)init_start;
        table->init.range = init_size;
        table->address = table_start;
        table->size = table_size;
-
-       /* See if the linker provided table looks valid. */
-       if (header_size <= 4
-           || header_start[0] != 1
-           || (void *)read_pointer(&ptr, end, header_start[1]) != table_start
-           || header_start[2] == DW_EH_PE_omit
-           || read_pointer(&ptr, end, header_start[2]) <= 0
-           || header_start[3] == DW_EH_PE_omit)
-               header_start = NULL;
-
+       /* To avoid the pointer addition with NULL pointer.*/
+       if (header_start != NULL) {
+               const u8 *ptr = header_start + 4;
+               const u8 *end = header_start + header_size;
+               /* See if the linker provided table looks valid. */
+               if (header_size <= 4
+               || header_start[0] != 1
+               || (void *)read_pointer(&ptr, end, header_start[1])
+                               != table_start
+               || header_start[2] == DW_EH_PE_omit
+               || read_pointer(&ptr, end, header_start[2]) <= 0
+               || header_start[3] == DW_EH_PE_omit)
+                       header_start = NULL;
+       }
        table->hdrsz = header_size;
        smp_wmb();
        table->header = header_start;
-- 
1.9.1



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