Patch "udf: limit the maximum number of indirect extents in a row" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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 4.4-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-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From b0918d9f476a8434b055e362b83fa4fd1d462c3f Mon Sep 17 00:00:00 2001
From: Vegard Nossum <vegard.nossum@oracle.com>
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@oracle.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@oracle.com>
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/udf/inode.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -2047,14 +2047,29 @@ 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@oracle.com are

queue-4.4/btrfs-handle-invalid-num_stripes-in-sys_array.patch
queue-4.4/iio-add-iio_trigger-dependency-to-stk8ba50.patch
queue-4.4/udf-limit-the-maximum-number-of-indirect-extents-in-a-row.patch
queue-4.4/iio-add-has_iomem-dependency-to-vf610_adc.patch