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Subject[PATCH] core: Catch overflows in do_div() function
Date
If second parameter passed to this function was 64 then it silently
truncates to 32 bits. Catch such situation.

Signed-off-by: Anatol Pomozov <anatol.pomozov@gmail.com>
---
include/asm-generic/div64.h | 3 +++
1 file changed, 3 insertions(+)

diff --git a/include/asm-generic/div64.h b/include/asm-generic/div64.h
index 8f4e319..84339a0 100644
--- a/include/asm-generic/div64.h
+++ b/include/asm-generic/div64.h
@@ -17,6 +17,7 @@
* beware of side effects!
*/

+#include <linux/bug.h>
#include <linux/types.h>
#include <linux/compiler.h>

@@ -25,6 +26,7 @@
# define do_div(n,base) ({ \
uint32_t __base = (base); \
uint32_t __rem; \
+ BUG_ON(sizeof(base) > 4 && base >= (1UL<<32)); \
__rem = ((uint64_t)(n)) % __base; \
(n) = ((uint64_t)(n)) / __base; \
__rem; \
@@ -40,6 +42,7 @@ extern uint32_t __div64_32(uint64_t *dividend, uint32_t divisor);
# define do_div(n,base) ({ \
uint32_t __base = (base); \
uint32_t __rem; \
+ BUG_ON(sizeof(base) > 4 && base >= (1UL<<32)); \
(void)(((typeof((n)) *)0) == ((uint64_t *)0)); \
if (likely(((n) >> 32) == 0)) { \
__rem = (uint32_t)(n) % __base; \
--
1.8.4


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