From: Taehee Yoo ap420073@gmail.com

commit 360cc79d9d299ce297b205508276285ceffc5fa8 upstream.

The table field in nft_obj_filter is not an array. In order to check tablename, we should check if the pointer is set.

Test commands:

%nft add table ip filter %nft add counter ip filter ct1 %nft reset counters

Splat looks like:

[ 306.510504] kasan: CONFIG_KASAN_INLINE enabled [ 306.516184] kasan: GPF could be caused by NULL-ptr deref or user memory access [ 306.524775] general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI [ 306.528284] Modules linked in: nft_objref nft_counter nf_tables nfnetlink ip_tables x_tables [ 306.528284] CPU: 0 PID: 1488 Comm: nft Not tainted 4.17.0-rc4+ #17 [ 306.528284] Hardware name: To be filled by O.E.M. To be filled by O.E.M./Aptio CRB, BIOS 5.6.5 07/08/2015 [ 306.528284] RIP: 0010:nf_tables_dump_obj+0x52c/0xa70 [nf_tables] [ 306.528284] RSP: 0018:ffff8800b6cb7520 EFLAGS: 00010246 [ 306.528284] RAX: 0000000000000000 RBX: ffff8800b6c49820 RCX: 0000000000000000 [ 306.528284] RDX: 0000000000000000 RSI: dffffc0000000000 RDI: ffffed0016d96e9a [ 306.528284] RBP: ffff8800b6cb75c0 R08: ffffed00236fce7c R09: ffffed00236fce7b [ 306.528284] R10: ffffffff9f6241e8 R11: ffffed00236fce7c R12: ffff880111365108 [ 306.528284] R13: 0000000000000000 R14: ffff8800b6c49860 R15: ffff8800b6c49860 [ 306.528284] FS: 00007f838b007700(0000) GS:ffff88011b600000(0000) knlGS:0000000000000000 [ 306.528284] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 306.528284] CR2: 00007ffeafabcf78 CR3: 00000000b6cbe000 CR4: 00000000001006f0 [ 306.528284] Call Trace: [ 306.528284] netlink_dump+0x470/0xa20 [ 306.528284] __netlink_dump_start+0x5ae/0x690 [ 306.528284] ? nf_tables_getobj+0x1b3/0x740 [nf_tables] [ 306.528284] nf_tables_getobj+0x2f5/0x740 [nf_tables] [ 306.528284] ? nft_obj_notify+0x100/0x100 [nf_tables] [ 306.528284] ? nf_tables_getobj+0x740/0x740 [nf_tables] [ 306.528284] ? nf_tables_dump_flowtable_done+0x70/0x70 [nf_tables] [ 306.528284] ? nft_obj_notify+0x100/0x100 [nf_tables] [ 306.528284] nfnetlink_rcv_msg+0x8ff/0x932 [nfnetlink] [ 306.528284] ? nfnetlink_rcv_msg+0x216/0x932 [nfnetlink] [ 306.528284] netlink_rcv_skb+0x1c9/0x2f0 [ 306.528284] ? nfnetlink_bind+0x1d0/0x1d0 [nfnetlink] [ 306.528284] ? debug_check_no_locks_freed+0x270/0x270 [ 306.528284] ? netlink_ack+0x7a0/0x7a0 [ 306.528284] ? ns_capable_common+0x6e/0x110 [ ... ]

Fixes: e46abbcc05aa8 ("netfilter: nf_tables: Allow table names of up to 255 chars") Signed-off-by: Taehee Yoo ap420073@gmail.com Acked-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Florian Westphal fw@strlen.de --- net/netfilter/nf_tables_api.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 60936bca3181..85b549e84104 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -4614,7 +4614,7 @@ static int nf_tables_dump_obj(struct sk_buff *skb, struct netlink_callback *cb) if (idx > s_idx) memset(&cb->args[1], 0, sizeof(cb->args) - sizeof(cb->args[0])); - if (filter && filter->table[0] && + if (filter && filter->table && strcmp(filter->table, table->name)) goto cont; if (filter &&