The patch titled
Subject: linux/kernel.h: fix overflow for DIV_ROUND_UP_ULL
has been added to the -mm tree. Its filename is
linux-kernelh-fix-overflow-for-div_round_up_ull.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/linux-kernelh-fix-overflow-for-div_round_up_ull.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/linux-kernelh-fix-overflow-for-div_round_up_ull.patch
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------------------------------------------------------
From: Vinod Koul <vkoul@xxxxxxxxxx>
Subject: linux/kernel.h: fix overflow for DIV_ROUND_UP_ULL
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.
Link: http://lkml.kernel.org/r/20190625100518.30753-1-vkoul@xxxxxxxxxx
Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kernel.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/include/linux/kernel.h~linux-kernelh-fix-overflow-for-div_round_up_ull
+++ a/include/linux/kernel.h
@@ -93,7 +93,8 @@
#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)
_
Patches currently in -mm which might be from vkoul@xxxxxxxxxx are
linux-kernelh-fix-overflow-for-div_round_up_ull.patch
