udf: limit the maximum number of indirect extents in a row
udf_next_aext() just follows extent pointers while extents are marked as indirect. This can loop forever for corrupted filesystem. Limit number the of indirect extents we are willing to follow in a row. [JK: Updated changelog, limit, style] Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Cc: stable@vger.kernel.org Cc: Jan Kara <jack@suse.com> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jan Kara <jack@suse.cz>
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@ -2047,14 +2047,29 @@ void udf_write_aext(struct inode *inode, struct extent_position *epos,
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epos->offset += adsize;
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}
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/*
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* Only 1 indirect extent in a row really makes sense but allow upto 16 in case
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* someone does some weird stuff.
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*/
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#define UDF_MAX_INDIR_EXTS 16
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int8_t udf_next_aext(struct inode *inode, struct extent_position *epos,
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struct kernel_lb_addr *eloc, uint32_t *elen, int inc)
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{
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int8_t etype;
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unsigned int indirections = 0;
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while ((etype = udf_current_aext(inode, epos, eloc, elen, inc)) ==
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(EXT_NEXT_EXTENT_ALLOCDECS >> 30)) {
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int block;
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if (++indirections > UDF_MAX_INDIR_EXTS) {
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udf_err(inode->i_sb,
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"too many indirect extents in inode %lu\n",
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inode->i_ino);
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return -1;
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}
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epos->block = *eloc;
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epos->offset = sizeof(struct allocExtDesc);
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brelse(epos->bh);
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