From: Alexander Lobakin alexandr.lobakin@intel.com
[ Upstream commit 428bc098635680a664779f26f24fe9197d186172 ]
GENMASK*() family takes the first and the last bits of the mask *including* them. So, with the current code bitmap_to_arr64() doesn't clear the tail properly:
nbits % exp mask must be 1 GENMASK(1, 0) 0x3 0x1 ... 63 GENMASK(63, 0) 0xffffffffffffffff 0x7fffffffffffffff
This was found by making the function always available instead of 32-bit BE systems only (for reusing in some new functionality). Turn the number of bits into the last bit set by subtracting 1. @nbits is already checked to be positive beforehand.
Fixes: 0a97953fd221 ("lib: add bitmap_{from,to}_arr64") Signed-off-by: Alexander Lobakin alexandr.lobakin@intel.com Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com Signed-off-by: Yury Norov yury.norov@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- lib/bitmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/bitmap.c b/lib/bitmap.c index b18e31ea6e66..e903e13c62e1 100644 --- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -1564,7 +1564,7 @@ void bitmap_to_arr64(u64 *buf, const unsigned long *bitmap, unsigned int nbits)
/* Clear tail bits in the last element of array beyond nbits. */ if (nbits % 64) - buf[-1] &= GENMASK_ULL(nbits % 64, 0); + buf[-1] &= GENMASK_ULL((nbits - 1) % 64, 0); } EXPORT_SYMBOL(bitmap_to_arr64); #endif