[PATCH 4.2.y-ckt 051/268] udf: limit the maximum number of indirect extents in a row
From: Kamal Mostafa <hidden>
Date: 2016-01-27 20:37:09
Also in:
lkml
Subsystem:
filesystems (vfs and infrastructure), the rest, udf filesystem · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds, Jan Kara
4.2.8-ckt3 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Vegard Nossum <redacted> 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 <redacted> Cc: Jan Kara <jack@suse.com> Cc: Quentin Casasnovas <redacted> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Kamal Mostafa <redacted> --- fs/udf/inode.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/fs/udf/inode.c b/fs/udf/inode.c
index 8d0b3ad..566df9b 100644
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c@@ -2047,14 +2047,29 @@ 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