From dd7cbca1f89109b0b64a3f44b5f991d0ee50f920 Mon Sep 17 00:00:00 2001 From: Alexander Lobakin Date: Mon, 11 Jul 2022 20:09:29 +0200 Subject: [PATCH] lib/bitmap: fix off-by-one in bitmap_to_arr64() 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: a1a19b185fa0 ("lib: add bitmap_{from,to}_arr64") Signed-off-by: Alexander Lobakin Reviewed-by: Andy Shevchenko Signed-off-by: Yury Norov --- lib/bitmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/bitmap.c b/lib/bitmap.c index b18e31ea6e664..e903e13c62e11 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 -- 2.39.5