Messages in this thread Patch in this message | | | From | Sasha Levin <> | Subject | [PATCH AUTOSEL 4.4 21/33] xfs: make sure the rt allocator doesn't run off the end | Date | Sun, 18 Oct 2020 15:27:16 -0400 |
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From: "Darrick J. Wong" <darrick.wong@oracle.com>
[ Upstream commit 2a6ca4baed620303d414934aa1b7b0a8e7bab05f ]
There's an overflow bug in the realtime allocator. If the rt volume is large enough to handle a single allocation request that is larger than the maximum bmap extent length and the rt bitmap ends exactly on a bitmap block boundary, it's possible that the near allocator will try to check the freeness of a range that extends past the end of the bitmap. This fails with a corruption error and shuts down the fs.
Therefore, constrain maxlen so that the range scan cannot run off the end of the rt bitmap.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Sasha Levin <sashal@kernel.org> --- fs/xfs/xfs_rtalloc.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c index 919b6544b61a3..bda5248fc6498 100644 --- a/fs/xfs/xfs_rtalloc.c +++ b/fs/xfs/xfs_rtalloc.c @@ -256,6 +256,9 @@ xfs_rtallocate_extent_block( end = XFS_BLOCKTOBIT(mp, bbno + 1) - 1; i <= end; i++) { + /* Make sure we don't scan off the end of the rt volume. */ + maxlen = min(mp->m_sb.sb_rextents, i + maxlen) - i; + /* * See if there's a free extent of maxlen starting at i. * If it's not so then next will contain the first non-free. @@ -447,6 +450,14 @@ xfs_rtallocate_extent_near( */ if (bno >= mp->m_sb.sb_rextents) bno = mp->m_sb.sb_rextents - 1; + + /* Make sure we don't run off the end of the rt volume. */ + maxlen = min(mp->m_sb.sb_rextents, bno + maxlen) - bno; + if (maxlen < minlen) { + *rtblock = NULLRTBLOCK; + return 0; + } + /* * Try the exact allocation first. */ -- 2.25.1
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