[34-longterm 130/247] ldm: corrupted partition table can cause kernel oops

Paul Gortmaker
2011-06-23T18:02:49Z

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 294f6cf48666825d23c9372ef37631232746e40d 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 changes ldm_parse_vmdb() to Validate the value of vblk_size.

Signed-off-by: Timo Warns <warns@pre-sense.de>
Cc: Eugene Teo <eugeneteo@kernel.sg>
Acked-by: Richard Russon <ldm@flatcap.org>
Cc: Harvey Harrison <harvey.harrison@gmail.com>
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 | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/fs/partitions/ldm.c b/fs/partitions/ldm.c
index 8652fb9..2cd9e43 100644
--- a/fs/partitions/ldm.c
+++ b/fs/partitions/ldm.c
@@ -251,6 +251,11 @@ static bool ldm_parse_vmdb (const u8 *data, struct vmdb *vm)
}

vm->vblk_size = get_unaligned_be32(data + 0x08);
+ if (vm->vblk_size == 0) {
+ ldm_error ("Illegal VBLK size");
+ return false;
+ }
+
vm->vblk_offset = get_unaligned_be32(data + 0x0C);
vm->last_vblk_seq = get_unaligned_be32(data + 0x04);

--
1.7.4.4