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[3.19.y-ckt,stable] Patch "udf: limit the maximum number of indirect extents in a row" has been added to the 3.19.y-ckt tree

Message ID 1454029632-9338-1-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa Jan. 29, 2016, 1:07 a.m. UTC 
This is a note to let you know that I have just added a patch titled

    udf: limit the maximum number of indirect extents in a row

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt14.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

From d32676ed3318f9c705eaa2bb6860a5ba3b7f77c7 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

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: Kamal Mostafa <kamal@canonical.com>
---
 fs/udf/inode.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

--
1.9.1
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Patch

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);