In the bitmap_ip_uadt function, if ip is greater than ip_to, they are swapped.
However, there is no check to see if ip is smaller than map->first, which
causes an out-of-bounds vulnerability. Therefore, you need to add a missing
bounds check to prevent out-of-bounds.

Cc: <stable@vger.kernel.org>
Reported-by: syzbot+58c872f7790a4d2ac951@syzkaller.appspotmail.com
Fixes: 72205fc68bd1 ("netfilter: ipset: bitmap:ip set type support")
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
---
 net/netfilter/ipset/ip_set_bitmap_ip.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/ipset/ip_set_bitmap_ip.c b/net/netfilter/ipset/ip_set_bitmap_ip.c
index e4fa00abde6a..705c316b001a 100644
--- a/net/netfilter/ipset/ip_set_bitmap_ip.c
+++ b/net/netfilter/ipset/ip_set_bitmap_ip.c
@@ -178,7 +178,7 @@ bitmap_ip_uadt(struct ip_set *set, struct nlattr *tb[],
 		ip_to = ip;
 	}
 
-	if (ip_to > map->last_ip)
+	if (ip < map->first_ip || ip_to > map->last_ip)
 		return -IPSET_ERR_BITMAP_RANGE;
 
 	for (; !before(ip_to, ip); ip += map->hosts) {
--

Hello Jeongjun,

On Tue, 12 Nov 2024, Jeongjun Park wrote:

> In the bitmap_ip_uadt function, if ip is greater than ip_to, they are swapped.
> However, there is no check to see if ip is smaller than map->first, which
> causes an out-of-bounds vulnerability. Therefore, you need to add a missing
> bounds check to prevent out-of-bounds.

It's a good catch, thanks! However, with the patch below the 

                        if (ip < map->first_ip)
                                return -IPSET_ERR_BITMAP_RANGE;

lines in the branch just after swapping the from/to addresses becomes 
unnecessary. Could you send a second version of the patch with the lines
above removed?

Best regards,
Jozsef

> Cc: <stable@vger.kernel.org>
> Reported-by: syzbot+58c872f7790a4d2ac951@syzkaller.appspotmail.com
> Fixes: 72205fc68bd1 ("netfilter: ipset: bitmap:ip set type support")
> Signed-off-by: Jeongjun Park <aha310510@gmail.com>
> ---
>  net/netfilter/ipset/ip_set_bitmap_ip.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/netfilter/ipset/ip_set_bitmap_ip.c b/net/netfilter/ipset/ip_set_bitmap_ip.c
> index e4fa00abde6a..705c316b001a 100644
> --- a/net/netfilter/ipset/ip_set_bitmap_ip.c
> +++ b/net/netfilter/ipset/ip_set_bitmap_ip.c
> @@ -178,7 +178,7 @@ bitmap_ip_uadt(struct ip_set *set, struct nlattr *tb[],
>  		ip_to = ip;
>  	}
>  
> -	if (ip_to > map->last_ip)
> +	if (ip < map->first_ip || ip_to > map->last_ip)
>  		return -IPSET_ERR_BITMAP_RANGE;
>  
>  	for (; !before(ip_to, ip); ip += map->hosts) {
> --
> 

-- 
E-mail : kadlec@netfilter.org, kadlec@blackhole.kfki.hu, kadlecsik.jozsef@wigner.hu
Address: Wigner Research Centre for Physics
         H-1525 Budapest 114, POB. 49, Hungary