fs/partitions/ldm.c: fix oops caused by corrupted partition table, CVE-2011-1017
 

On Tue, 2011-04-26 at 11:44 -0700, Brad Figg wrote:
> From: Timo Warns <Warns@pre-sense.de>
>
> BugLink: http://bugs.launchpad.net/bugs/771382
>
> CVE-2011-1017
>
> 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>
>
> (backported from commit c340b1d640001c8c9ecff74f68fd90422ae2448a)
> Signed-off-by: Brad Figg <brad.figg@canonical.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 7ab1c11..c861f52 100644
> --- a/fs/partitions/ldm.c
> +++ b/fs/partitions/ldm.c
> @@ -1225,6 +1225,11 @@ 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 = BE32 (data + 0x08);
> rec = BE16 (data + 0x0C);
> num = BE16 (data + 0x0E);
> @@ -1232,6 +1237,10 @@ 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);
> @@ -1260,10 +1269,9 @@ 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;
> --
> 1.7.0.4
>
>
Acked-by: Steve Conklin <sconklin@canonical.com>

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