[PATCH AUTOSEL 4.14 13/13] linux/kernel.h: fix overflow for DIV_ROUND_UP_ULL

[Sasha Levin <sashal@kernel.org>]

From: Vinod Koul <vkoul@kernel.org>

[ Upstream commit 8f9fab480c7a87b10bb5440b5555f370272a5d59 ]

DIV_ROUND_UP_ULL adds the two arguments and then invokes
DIV_ROUND_DOWN_ULL.  But on a 32bit system the addition of two 32 bit
values can overflow.  DIV_ROUND_DOWN_ULL does it correctly and stashes
the addition into a unsigned long long so cast the result to unsigned
long long here to avoid the overflow condition.

[akpm@linux-foundation.org: DIV_ROUND_UP_ULL must be an rval]
Link: http://lkml.kernel.org/r/20190625100518.30753-1-vkoul@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/kernel.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 1c5469adaa85..bb7baecef002 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -101,7 +101,8 @@
 #define DIV_ROUND_DOWN_ULL(ll, d) \
 	({ unsigned long long _tmp = (ll); do_div(_tmp, d); _tmp; })
 
-#define DIV_ROUND_UP_ULL(ll, d)		DIV_ROUND_DOWN_ULL((ll) + (d) - 1, (d))
+#define DIV_ROUND_UP_ULL(ll, d) \
+	DIV_ROUND_DOWN_ULL((unsigned long long)(ll) + (d) - 1, (d))
 
 #if BITS_PER_LONG == 32
 # define DIV_ROUND_UP_SECTOR_T(ll,d) DIV_ROUND_UP_ULL(ll, d)
-- 
2.20.1