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| author | Alexander Lobakin <alexandr.lobakin@intel.com> | 2022-07-11 20:09:29 +0200 |
|---|---|---|
| committer | Yury Norov <yury.norov@gmail.com> | 2022-07-12 08:00:50 -0700 |
| commit | 428bc098635680a664779f26f24fe9197d186172 (patch) | |
| tree | 97d3d4a3edbdce777501739e5da830efd461957c /lib/bitmap.c | |
| parent | dc34d5036692c614eef23c1130ee42a201c316bf (diff) | |
| download | lwn-428bc098635680a664779f26f24fe9197d186172.tar.gz lwn-428bc098635680a664779f26f24fe9197d186172.zip | |
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: 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>
Diffstat (limited to 'lib/bitmap.c')
| -rw-r--r-- | lib/bitmap.c | 2 |
1 files changed, 1 insertions, 1 deletions
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 |