diff options
| author | Darrick J. Wong <darrick.wong@oracle.com> | 2019-08-19 17:39:32 -0700 |
|---|---|---|
| committer | Darrick J. Wong <darrick.wong@oracle.com> | 2019-08-26 13:54:37 -0700 |
| commit | ced90841f43e170d9b2ad0aa1d493f37e03e3de0 (patch) | |
| tree | 27dfb6c43ddb0c8ddfeaeafed6864e67e712eb87 | |
| parent | 59e1323c49a107e360cba5636d23acfc6c933cf1 (diff) | |
xfs: fix sign handling problem in xfs_bmbt_diff_two_keysxfs-5.4-fixes_2019-08-26
In xfs_bmbt_diff_two_keys, we perform a signed int64_t subtraction with
two unsigned 64-bit quantities. If the second quantity is actually the
"maximum" key (all ones) as used in _query_all, the subtraction
effectively becomes addition of two positive numbers and the function
returns incorrect results. Fix this with explicit comparisons of the
unsigned values.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
| -rw-r--r-- | fs/xfs/libxfs/xfs_bmap_btree.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/fs/xfs/libxfs/xfs_bmap_btree.c b/fs/xfs/libxfs/xfs_bmap_btree.c index fbb18ba5d905..3c1a805b3775 100644 --- a/fs/xfs/libxfs/xfs_bmap_btree.c +++ b/fs/xfs/libxfs/xfs_bmap_btree.c @@ -400,8 +400,20 @@ xfs_bmbt_diff_two_keys( union xfs_btree_key *k1, union xfs_btree_key *k2) { - return (int64_t)be64_to_cpu(k1->bmbt.br_startoff) - - be64_to_cpu(k2->bmbt.br_startoff); + uint64_t a = be64_to_cpu(k1->bmbt.br_startoff); + uint64_t b = be64_to_cpu(k2->bmbt.br_startoff); + + /* + * Note: This routine previously casted a and b to int64 and subtracted + * them to generate a result. This lead to problems if b was the + * "maximum" key value (all ones) being signed incorrectly, hence this + * somewhat less efficient version. + */ + if (a > b) + return 1; + else if (b > a) + return -1; + return 0; } static xfs_failaddr_t |