Re: [PATCH 3/3] libceph: fix overflow in osdmap_apply_incremental()

[Alex Elder <elder@dreamhost.com>]

On 04/29/2012 01:59 AM, Xi Wang wrote:
> On 32-bit systems, a large `pglen' would overflow `pglen*sizeof(u32)'
> and bypass the check ceph_decode_need(p, end, pglen*sizeof(u32), bad).
> It would also overflow the subsequent kmalloc() size, leading to
> out-of-bounds write.
> 
> Signed-off-by: Xi Wang <xi.wang@gmail.com>

This looks good.  I'll wait to hear back on my comments on
your earlier patches before committing these.

Reviewed-by: Alex Elder <elder@inktank.com>

> ---
>  net/ceph/osdmap.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
> index 774eac6..b1ea6d1 100644
> --- a/net/ceph/osdmap.c
> +++ b/net/ceph/osdmap.c
> @@ -891,6 +891,10 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
>  
>  		if (pglen) {
>  			/* insert */
> +			if (pglen > (UINT_MAX - sizeof(*pg)) / sizeof(u32)) {
> +				err = -EINVAL;
> +				goto bad;
> +			}
>  			ceph_decode_need(p, end, pglen*sizeof(u32), bad);
>  			pg = kmalloc(sizeof(*pg) + sizeof(u32)*pglen, GFP_NOFS);
>  			if (!pg) {