| From | Kamal Mostafa <> | Subject | [PATCH 3.13 151/162] lib/bitmap.c: fix undefined shift in __bitmap_shift_{left|right}() | Date | Thu, 6 Nov 2014 14:36:55 -0800 |
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3.13.11.11 -stable review patch. If anyone has any objections, please let me know.
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From: Jan Kara <jack@suse.cz>
commit ea5d05b34aca25c066e0699512d0ffbd8ee6ac3e upstream.
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 Signed-off-by: Jan Kara <jack@suse.cz> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- lib/bitmap.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/lib/bitmap.c b/lib/bitmap.c index 06f7e4f..e5c4ebe 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; } -- 1.9.1
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