On 04/29/2012 02:07 AM, Xi Wang wrote:
> `len' is read from network and thus needs validation. Otherwise a
> large `len' would cause out-of-bounds access via the memcpy() call.
> In addition, len = 0xffffffff would overflow the kmalloc() size,
> leading to out-of-bounds write.
>
> This patch adds a check of `len' via ceph_decode_need(). Also use
> kstrndup rather than kmalloc/memcpy.
This looks good, however I'd like to correct one thing, and fix
another (both noted below) before committing. Please confirm/ack my
suggested change; I'll still credit you with the original patch.
Thanks.
-Alex
> Signed-off-by: Xi Wang <[email protected]>
> ---
> Subject corrected. Sorry, my bad.
> ---
> net/ceph/osdmap.c | 9 +++------
> 1 files changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
> index 29ad46e..f80afc3 100644
> --- a/net/ceph/osdmap.c
> +++ b/net/ceph/osdmap.c
> @@ -495,15 +495,12 @@ static int __decode_pool_names(void **p, void *end,
> struct ceph_osdmap *map)
> ceph_decode_32_safe(p, end, pool, bad);
> ceph_decode_32_safe(p, end, len, bad);
> dout(" pool %d len %d\n", pool, len);
> + ceph_decode_need(p, end, len, bad);
> pi = __lookup_pg_pool(&map->pg_pools, pool);
> if (pi) {
> kfree(pi->name);
> - pi->name = kmalloc(len + 1, GFP_NOFS);
> - if (pi->name) {
> - memcpy(pi->name, *p, len);
> - pi->name[len] = '\0';
> - dout(" name is %s\n", pi->name);
> - }
> + pi->name = kstrndup(*p, len, GFP_NOFS);
> + dout(" name is %s\n", pi->name);
Instead:
if (pi) {
char *name = kstrndup(*p, len, GFP_NOFS);
if (!name)
return -ENOMEM;
kfree(pi->name);
pi->name = name;
dout(" name is %s\n", pi->name);
}
> }
> *p += len;
> }
--
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