netdev - [PATCH 8/9] netfilter: nf_tables: fix NULL-ptr in nf_tables_dump

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180528234221.31254-9-pablo@netfilter.org>
Date:   Tue, 29 May 2018 01:42:20 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     netfilter-devel@...r.kernel.org
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 8/9] netfilter: nf_tables: fix NULL-ptr in nf_tables_dump_obj()

From: Taehee Yoo <ap420073@...il.com>

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@...il.com>
Acked-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 net/netfilter/nf_tables_api.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 91e80aa852d6..2bdc8767aa40 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -4706,7 +4706,7 @@ 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 &&
@@ -5380,7 +5380,7 @@ static int nf_tables_dump_flowtable(struct sk_buff *skb,
 			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;
 
-- 
2.11.0