Re: [PATCH net-next v4 1/7] net: nexthop: Adjust netlink policy parsing for a new attribute
From: Eric Dumazet <edumazet@google.com>
Date: 2024-03-09 15:02:50
On Wed, Mar 6, 2024 at 1:50 PM Petr Machata [off-list ref] wrote:
quoted hunk ↗ jump to hunk
A following patch will introduce a new attribute, op-specific flags to adjust the behavior of an operation. Different operations will recognize different flags. - To make the differentiation possible, stop sharing the policies for get and del operations. - To allow querying for presence of the attribute, have all the attribute arrays sized to NHA_MAX, regardless of what is permitted by policy, and pass the corresponding value to nlmsg_parse() as well. Signed-off-by: Petr Machata <petrm@nvidia.com> Reviewed-by: David Ahern <dsahern@kernel.org> Reviewed-by: Ido Schimmel <idosch@nvidia.com> --- net/ipv4/nexthop.c | 58 ++++++++++++++++++++++------------------------ 1 file changed, 28 insertions(+), 30 deletions(-)diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c index 70509da4f080..bcd4df2f1cad 100644 --- a/net/ipv4/nexthop.c +++ b/net/ipv4/nexthop.c@@ -43,6 +43,10 @@ static const struct nla_policy rtm_nh_policy_get[] = { [NHA_ID] = { .type = NLA_U32 }, }; +static const struct nla_policy rtm_nh_policy_del[] = { + [NHA_ID] = { .type = NLA_U32 }, +};
Bogus repeated pattern in this patch. rtm_nh_policy_del[] has only NHA_ID entry defined. So the array size is small.
quoted hunk ↗ jump to hunk
+ static const struct nla_policy rtm_nh_policy_dump[] = { [NHA_OIF] = { .type = NLA_U32 }, [NHA_GROUPS] = { .type = NLA_FLAG },@@ -2966,9 +2970,9 @@ static int rtm_new_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh, return err; }
...
-
/* rtnl */
static int rtm_del_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack)
{
struct net *net = sock_net(skb->sk);
+ struct nlattr *tb[NHA_MAX + 1];big tb[] array, but small rtm_nh_policy_del[] policy.
quoted hunk ↗ jump to hunk
struct nl_info nlinfo = { .nlh = nlh, .nl_net = net,@@ -3020,7 +3010,12 @@ static int rtm_del_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh, int err; u32 id; - err = nh_valid_get_del_req(nlh, &id, extack); + err = nlmsg_parse(nlh, sizeof(struct nhmsg), tb, NHA_MAX,
But here you pass NHA_MAX...
+ rtm_nh_policy_del, extack); + if (err < 0) + return err;
So we hit : kernel BUG at lib/nlattr.c:411 ! invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 1 PID: 14369 Comm: syz-executor.2 Not tainted 6.8.0-rc7-syzkaller-02415-g2f901582f032 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024 RIP: 0010:validate_nla lib/nlattr.c:411 [inline] RIP: 0010:__nla_validate_parse+0x2f61/0x2f70 lib/nlattr.c:635 Code: 48 8b 4c 24 18 80 e1 07 38 c1 0f 8c e0 f7 ff ff 48 8b 7c 24 18 e8 ff 0e 1d fd e9 d1 f7 ff ff e8 d5 c2 91 06 e8 50 64 ba fc 90 <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 90 90 90 90 90 90 90 RSP: 0018:ffffc90003c1eec0 EFLAGS: 00010287 RAX: ffffffff84d90ad0 RBX: ffffffff8caa11b0 RCX: 0000000000040000 RDX: ffffc9000499a000 RSI: 000000000000065e RDI: 000000000000065f RBP: ffffc90003c1f100 R08: ffffffff84d8df5b R09: 0000000000000000 R10: ffffc90003c1f1a0 R11: fffff52000783e46 R12: 0000000000000008 R13: 1ffff1100f9c4183 R14: 000000000000006e R15: 0000000000000005 FS: 00007f5fe2d916c0(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020000440 CR3: 00000000229a2000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> __nla_parse+0x40/0x60 lib/nlattr.c:732 __nlmsg_parse include/net/netlink.h:756 [inline] nlmsg_parse include/net/netlink.h:777 [inline] rtm_del_nexthop+0x257/0x6d0 net/ipv4/nexthop.c:3256 rtnetlink_rcv_msg+0x89b/0x10d0 net/core/rtnetlink.c:6595 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2556 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline] netlink_unicast+0x7ea/0x980 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x8e0/0xcb0 net/netlink/af_netlink.c:1902 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:745 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2584 ___sys_sendmsg net/socket.c:2638 [inline] __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667 do_syscall_64+0xf9/0x240 entry_SYSCALL_64_after_hwframe+0x6f/0x77 RIP: 0033:0x7f5fe207dda9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f5fe2d910c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f5fe21abf80 RCX: 00007f5fe207dda9 RDX: 0000000000000000 RSI: 0000000020000440 RDI: 0000000000000003 RBP: 00007f5fe20ca47a R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007f5fe21abf80 R15: 00007fff7d5a1278