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xfs: catch bad block numbers freeing extents.

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A fuzzed filesystem crashed a kernel when freeing an extent with a
block number beyond the end of the filesystem. Convert all the debug
asserts in xfs_free_extent() to active checks so that we catch bad
extents and return that the filesytsem is corrupted rather than
crashing.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
This commit is contained in:
Dave Chinner 2011-04-08 12:45:07 +10:00 committed by Dave Chinner
parent fd074841cf
commit be65b18a10
1 changed files with 23 additions and 7 deletions
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30
fs/xfs/xfs_alloc.c
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@ -2395,17 +2395,33 @@ xfs_free_extent(
memset(&args, 0, sizeof(xfs_alloc_arg_t));
args.tp = tp;
args.mp = tp->t_mountp;
/*
* validate that the block number is legal - the enables us to detect
* and handle a silent filesystem corruption rather than crashing.
*/
args.agno = XFS_FSB_TO_AGNO(args.mp, bno);
ASSERT(args.agno < args.mp->m_sb.sb_agcount);
if (args.agno >= args.mp->m_sb.sb_agcount)
return EFSCORRUPTED;
args.agbno = XFS_FSB_TO_AGBNO(args.mp, bno);
if (args.agbno >= args.mp->m_sb.sb_agblocks)
return EFSCORRUPTED;
args.pag = xfs_perag_get(args.mp, args.agno);
if ((error = xfs_alloc_fix_freelist(&args, XFS_ALLOC_FLAG_FREEING)))
ASSERT(args.pag);
error = xfs_alloc_fix_freelist(&args, XFS_ALLOC_FLAG_FREEING);
if (error)
goto error0;
#ifdef DEBUG
ASSERT(args.agbp != NULL);
ASSERT((args.agbno + len) <=
be32_to_cpu(XFS_BUF_TO_AGF(args.agbp)->agf_length));
#endif
/* validate the extent size is legal now we have the agf locked */
if (args.agbno + len >
be32_to_cpu(XFS_BUF_TO_AGF(args.agbp)->agf_length)) {
error = EFSCORRUPTED;
goto error0;
}
error = xfs_free_ag_extent(tp, args.agbp, args.agno, args.agbno, len, 0);
error0:
xfs_perag_put(args.pag);