From: Jan Kara <[email protected]> Subject: lib/bitmap.c: fix undefined shift in __bitmap_shift_{left|right}()
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 <[email protected]> Cc: Rasmus Villemoes <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> --- lib/bitmap.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff -puN lib/bitmap.c~bitmap-fix-undefined-shift-in-__bitmap_shift_leftright lib/bitmap.c --- a/lib/bitmap.c~bitmap-fix-undefined-shift-in-__bitmap_shift_leftright +++ a/lib/bitmap.c @@ -131,7 +131,9 @@ void __bitmap_shift_right(unsigned long 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 * 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; } _ -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
