linux-kernel - [34-longterm 224/247] fs/partitions/ldm.c: fix oops caused by corrupted partition table

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Message-Id: <1308850515-15242-165-git-send-email-paul.gortmaker@windriver.com>
Date:	Thu, 23 Jun 2011 13:34:52 -0400
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	stable@...nel.org, linux-kernel@...r.kernel.org
Cc:	stable-review@...nel.org, Timo Warns <Warns@...-sense.de>,
	Timo Warns <warns@...-sense.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [34-longterm 224/247] fs/partitions/ldm.c: fix oops caused by corrupted partition table

From: Timo Warns <Warns@...-sense.de>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit c340b1d640001c8c9ecff74f68fd90422ae2448a upstream.

The kernel automatically evaluates partition tables of storage devices.
The code for evaluating LDM partitions (in fs/partitions/ldm.c) contains
a bug that causes a kernel oops on certain corrupted LDM partitions.
A kernel subsystem seems to crash, because, after the oops, the kernel no
longer recognizes newly connected storage devices.

The patch validates the value of vblk_size.

[akpm@...ux-foundation.org: coding-style fixes]
Signed-off-by: Timo Warns <warns@...-sense.de>
Cc: Eugene Teo <eugeneteo@...nel.sg>
Cc: Harvey Harrison <harvey.harrison@...il.com>
Cc: Richard Russon <rich@...tcap.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 fs/partitions/ldm.c |   16 ++++++++++++----
 1 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/fs/partitions/ldm.c b/fs/partitions/ldm.c
index 2cd9e43..a2a14cd 100644
--- a/fs/partitions/ldm.c
+++ b/fs/partitions/ldm.c
@@ -1299,6 +1299,11 @@ static bool ldm_frag_add (const u8 *data, int size, struct list_head *frags)
 
 	BUG_ON (!data || !frags);
 
+	if (size < 2 * VBLK_SIZE_HEAD) {
+		ldm_error("Value of size is to small.");
+		return false;
+	}
+
 	group = get_unaligned_be32(data + 0x08);
 	rec   = get_unaligned_be16(data + 0x0C);
 	num   = get_unaligned_be16(data + 0x0E);
@@ -1306,6 +1311,10 @@ static bool ldm_frag_add (const u8 *data, int size, struct list_head *frags)
 		ldm_error ("A VBLK claims to have %d parts.", num);
 		return false;
 	}
+	if (rec >= num) {
+		ldm_error("REC value (%d) exceeds NUM value (%d)", rec, num);
+		return false;
+	}
 
 	list_for_each (item, frags) {
 		f = list_entry (item, struct frag, list);
@@ -1334,10 +1343,9 @@ found:
 
 	f->map |= (1 << rec);
 
-	if (num > 0) {
-		data += VBLK_SIZE_HEAD;
-		size -= VBLK_SIZE_HEAD;
-	}
+	data += VBLK_SIZE_HEAD;
+	size -= VBLK_SIZE_HEAD;
+
 	memcpy (f->data+rec*(size-VBLK_SIZE_HEAD)+VBLK_SIZE_HEAD, data, size);
 
 	return true;
-- 
1.7.4.4

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