This is a note to let you know that I've just added the patch titled udf: limit the maximum number of indirect extents in a row to the 3.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: udf-limit-the-maximum-number-of-indirect-extents-in-a-row.patch and it can be found in the queue-3.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From b0918d9f476a8434b055e362b83fa4fd1d462c3f Mon Sep 17 00:00:00 2001 From: Vegard Nossum <vegard.nossum@xxxxxxxxxx> Date: Fri, 11 Dec 2015 15:54:16 +0100 Subject: udf: limit the maximum number of indirect extents in a row From: Vegard Nossum <vegard.nossum@xxxxxxxxxx> 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@xxxxxxxxxx> Cc: Jan Kara <jack@xxxxxxxx> Cc: Quentin Casasnovas <quentin.casasnovas@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Jan Kara <jack@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/udf/inode.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) --- a/fs/udf/inode.c +++ b/fs/udf/inode.c @@ -2055,14 +2055,29 @@ void udf_write_aext(struct inode *inode, 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); Patches currently in stable-queue which might be from vegard.nossum@xxxxxxxxxx are queue-3.10/udf-limit-the-maximum-number-of-indirect-extents-in-a-row.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html