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

Paul Gortmaker
2011-06-23T17:42:22Z

From: Timo Warns <Warns@pre-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@linux-foundation.org: coding-style fixes]
Signed-off-by: Timo Warns <warns@pre-sense.de>
Cc: Eugene Teo <eugeneteo@kernel.sg>
Cc: Harvey Harrison <harvey.harrison@gmail.com>
Cc: Richard Russon <rich@flatcap.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.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