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Date: Thu, 28 Jan 2016 17:16:14 -0800 From: Kamal Mostafa <kamal@...onical.com> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org, kernel-team@...ts.ubuntu.com Cc: Vegard Nossum <vegard.nossum@...cle.com>, Jan Kara <jack@...e.com>, Quentin Casasnovas <quentin.casasnovas@...cle.com>, Andrew Morton <akpm@...ux-foundation.org>, Jan Kara <jack@...e.cz>, Kamal Mostafa <kamal@...onical.com> Subject: [PATCH 3.19.y-ckt 036/210] udf: limit the maximum number of indirect extents in a row 3.19.8-ckt14 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Vegard Nossum <vegard.nossum@...cle.com> commit b0918d9f476a8434b055e362b83fa4fd1d462c3f upstream. 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@...cle.com> Cc: Jan Kara <jack@...e.com> Cc: Quentin Casasnovas <quentin.casasnovas@...cle.com> Cc: Andrew Morton <akpm@...ux-foundation.org> Signed-off-by: Jan Kara <jack@...e.cz> Signed-off-by: Kamal Mostafa <kamal@...onical.com> --- fs/udf/inode.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/fs/udf/inode.c b/fs/udf/inode.c index 7b72b7d..9ae690d 100644 --- a/fs/udf/inode.c +++ b/fs/udf/inode.c @@ -2054,14 +2054,29 @@ void udf_write_aext(struct inode *inode, struct extent_position *epos, epos->offset += adsize; } +/* + * Only 1 indirect extent in a row really makes sense but allow upto 16 in case + * someone does some weird stuff. + */ +#define UDF_MAX_INDIR_EXTS 16 + int8_t udf_next_aext(struct inode *inode, struct extent_position *epos, struct kernel_lb_addr *eloc, uint32_t *elen, int inc) { int8_t etype; + unsigned int indirections = 0; while ((etype = udf_current_aext(inode, epos, eloc, elen, inc)) == (EXT_NEXT_EXTENT_ALLOCDECS >> 30)) { int block; + + if (++indirections > UDF_MAX_INDIR_EXTS) { + udf_err(inode->i_sb, + "too many indirect extents in inode %lu\n", + inode->i_ino); + return -1; + } + epos->block = *eloc; epos->offset = sizeof(struct allocExtDesc); brelse(epos->bh); -- 1.9.1
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