If __bitmap_shift_left() or __bitmap_shift_right() are asked to shift by
a multiple of BITS_PER_LONG, they will try to shift a long value by
BITS_PER_LONG bits which is undefined. Change the functions to avoid the
undefined shift.

Coverity-id: 1192175
Coverity-id: 1192174
CC: Rasmus Villemoes <li...@rasmusvillemoes.dk>
CC: sta...@vger.kernel.org
Signed-off-by: Jan Kara <j...@suse.cz>
---
 lib/bitmap.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/lib/bitmap.c b/lib/bitmap.c
index cd250a2e14cb..b499ab6ada29 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -131,7 +131,9 @@ void __bitmap_shift_right(unsigned long *dst,
                lower = src[off + k];
                if (left && off + k == lim - 1)
                        lower &= mask;
-               dst[k] = upper << (BITS_PER_LONG - rem) | lower >> rem;
+               dst[k] = lower >> rem;
+               if (rem)
+                       dst[k] |= upper << (BITS_PER_LONG - rem);
                if (left && k == lim - 1)
                        dst[k] &= mask;
        }
@@ -172,7 +174,9 @@ void __bitmap_shift_left(unsigned long *dst,
                upper = src[k];
                if (left && k == lim - 1)
                        upper &= (1UL << left) - 1;
-               dst[k + off] = lower  >> (BITS_PER_LONG - rem) | upper << rem;
+               dst[k + off] = upper << rem;
+               if (rem)
+                       dst[k + off] |= lower >> (BITS_PER_LONG - rem);
                if (left && k + off == lim - 1)
                        dst[k + off] &= (1UL << left) - 1;
        }
-- 
1.8.1.4

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