xfs: catch invalid negative blknos in _xfs_buf_find()
Here blkno is a daddr_t, which is a __s64; it's possible to hold a value which is negative, and thus pass the (blkno >= eofs) test. Then we try to do a xfs_perag_get() for a ridiculous agno via xfs_daddr_to_agno(), and bad things happen when that fails, and returns a null pag which is dereferenced shortly thereafter. Found via a user-supplied fuzzed image... Signed-off-by: Eric Sandeen <sandeen@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
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@ -461,7 +461,7 @@ _xfs_buf_find(
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* have to check that the buffer falls within the filesystem bounds.
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*/
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eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_mount->m_sb.sb_dblocks);
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if (blkno >= eofs) {
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if (blkno < 0 || blkno >= eofs) {
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/*
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* XXX (dgc): we should really be returning -EFSCORRUPTED here,
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* but none of the higher level infrastructure supports
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