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authorVinod Koul <vkoul@kernel.org>2019-06-28 12:07:21 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-06-29 16:43:45 +0800
commit8f9fab480c7a87b10bb5440b5555f370272a5d59 (patch)
treea7980854d30c6713bfc9ca225fb1f79fc6274327
parent1a5f439c7c02837d943e528d46501564d4226757 (diff)
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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. [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>
-rw-r--r--include/linux/kernel.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 74b1ee9027f5..0c9bc231107f 100644
--- a/include/linux/kernel.h
+++ b/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)