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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>
This commit is contained in:
Vegard Nossum 2015-12-11 15:54:16 +01:00 committed by Jan Kara
parent e7a4eb8612
commit b0918d9f47
1 changed files with 15 additions and 0 deletions
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15
fs/udf/inode.c
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@ -2047,14 +2047,29 @@ void udf_write_aext(struct inode *inode, struct extent_position *epos,
epos->offset += adsize; 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, int8_t udf_next_aext(struct inode *inode, struct extent_position *epos,
struct kernel_lb_addr *eloc, uint32_t *elen, int inc) struct kernel_lb_addr *eloc, uint32_t *elen, int inc)
{ {
int8_t etype; int8_t etype;
unsigned int indirections = 0;
while ((etype = udf_current_aext(inode, epos, eloc, elen, inc)) == while ((etype = udf_current_aext(inode, epos, eloc, elen, inc)) ==
(EXT_NEXT_EXTENT_ALLOCDECS >> 30)) { (EXT_NEXT_EXTENT_ALLOCDECS >> 30)) {
int block; 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->block = *eloc;
epos->offset = sizeof(struct allocExtDesc); epos->offset = sizeof(struct allocExtDesc);
brelse(epos->bh); brelse(epos->bh);