ldm: corrupted partition table can cause kernel oops

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>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/partitions/ldm.c b/fs/partitions/ldm.c
index 789c625c7aa5..b10e3540d5b7 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);