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Date: Tue, 4 Apr 2023 10:46:15 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Kuniyuki Iwashima <kuniyu@...zon.com>
Cc: "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Kuniyuki Iwashima <kuni1840@...il.com>, netdev@...r.kernel.org,
syzbot <syzkaller@...glegroups.com>,
"Dae R . Jeong" <threeearcat@...il.com>
Subject: Re: [PATCH v1 net 1/2] raw: Fix NULL deref in raw_get_next().
On Tue, Apr 4, 2023 at 4:02 AM Kuniyuki Iwashima <kuniyu@...zon.com> wrote:
>
> Dae R. Jeong reported a NULL deref in raw_get_next() [0].
>
> It seems that the repro was running these sequences in parallel so
> that one thread was iterating on a socket that was being freed in
> another netns.
>
> unshare(0x40060200)
> r0 = syz_open_procfs(0x0, &(0x7f0000002080)='net/raw\x00')
> socket$inet_icmp_raw(0x2, 0x3, 0x1)
> pread64(r0, &(0x7f0000000000)=""/10, 0xa, 0x10000000007f)
>
> After commit 0daf07e52709 ("raw: convert raw sockets to RCU"), we
> use RCU and hlist_nulls_for_each_entry() to iterate over SOCK_RAW
> sockets. However, we should use spinlock for slow paths to avoid
> the NULL deref.
>
> Also, SOCK_RAW does not use SLAB_TYPESAFE_BY_RCU, and the slab object
> is not reused during iteration in the grace period. In fact, the
> lockless readers do not check the nulls marker with get_nulls_value().
> So, SOCK_RAW should use hlist instead of hlist_nulls.
>
> Instead of adding an unnecessary barrier by sk_nulls_for_each_rcu(),
> let's convert hlist_nulls to hlist and use sk_for_each_rcu() for
> fast paths and sk_for_each() and spinlock for /proc/net/raw.
>
> [0]:
> general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] PREEMPT SMP KASAN
> KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
> CPU: 2 PID: 20952 Comm: syz-executor.0 Not tainted 6.2.0-g048ec869bafd-dirty #7
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
> RIP: 0010:read_pnet include/net/net_namespace.h:383 [inline]
> RIP: 0010:sock_net include/net/sock.h:649 [inline]
> RIP: 0010:raw_get_next net/ipv4/raw.c:974 [inline]
> RIP: 0010:raw_get_idx net/ipv4/raw.c:986 [inline]
> RIP: 0010:raw_seq_start+0x431/0x800 net/ipv4/raw.c:995
> Code: ef e8 33 3d 94 f7 49 8b 6d 00 4c 89 ef e8 b7 65 5f f7 49 89 ed 49 83 c5 98 0f 84 9a 00 00 00 48 83 c5 c8 48 89 e8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 ef e8 00 3d 94 f7 4c 8b 7d 00 48 89 ef
> RSP: 0018:ffffc9001154f9b0 EFLAGS: 00010206
> RAX: 0000000000000005 RBX: 1ffff1100302c8fd RCX: 0000000000000000
> RDX: 0000000000000028 RSI: ffffc9001154f988 RDI: ffffc9000f77a338
> RBP: 0000000000000029 R08: ffffffff8a50ffb4 R09: fffffbfff24b6bd9
> R10: fffffbfff24b6bd9 R11: 0000000000000000 R12: ffff88801db73b78
> R13: fffffffffffffff9 R14: dffffc0000000000 R15: 0000000000000030
> FS: 00007f843ae8e700(0000) GS:ffff888063700000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000055bb9614b35f CR3: 000000003c672000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> <TASK>
> seq_read_iter+0x4c6/0x10f0 fs/seq_file.c:225
> seq_read+0x224/0x320 fs/seq_file.c:162
> pde_read fs/proc/inode.c:316 [inline]
> proc_reg_read+0x23f/0x330 fs/proc/inode.c:328
> vfs_read+0x31e/0xd30 fs/read_write.c:468
> ksys_pread64 fs/read_write.c:665 [inline]
> __do_sys_pread64 fs/read_write.c:675 [inline]
> __se_sys_pread64 fs/read_write.c:672 [inline]
> __x64_sys_pread64+0x1e9/0x280 fs/read_write.c:672
> do_syscall_x64 arch/x86/entry/common.c:51 [inline]
> do_syscall_64+0x4e/0xa0 arch/x86/entry/common.c:82
> entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x478d29
> Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 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 bc ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f843ae8dbe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000011
> RAX: ffffffffffffffda RBX: 0000000000791408 RCX: 0000000000478d29
> RDX: 000000000000000a RSI: 0000000020000000 RDI: 0000000000000003
> RBP: 00000000f477909a R08: 0000000000000000 R09: 0000000000000000
> R10: 000010000000007f R11: 0000000000000246 R12: 0000000000791740
> R13: 0000000000791414 R14: 0000000000791408 R15: 00007ffc2eb48a50
> </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:read_pnet include/net/net_namespace.h:383 [inline]
> RIP: 0010:sock_net include/net/sock.h:649 [inline]
> RIP: 0010:raw_get_next net/ipv4/raw.c:974 [inline]
> RIP: 0010:raw_get_idx net/ipv4/raw.c:986 [inline]
> RIP: 0010:raw_seq_start+0x431/0x800 net/ipv4/raw.c:995
> Code: ef e8 33 3d 94 f7 49 8b 6d 00 4c 89 ef e8 b7 65 5f f7 49 89 ed 49 83 c5 98 0f 84 9a 00 00 00 48 83 c5 c8 48 89 e8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 ef e8 00 3d 94 f7 4c 8b 7d 00 48 89 ef
> RSP: 0018:ffffc9001154f9b0 EFLAGS: 00010206
> RAX: 0000000000000005 RBX: 1ffff1100302c8fd RCX: 0000000000000000
> RDX: 0000000000000028 RSI: ffffc9001154f988 RDI: ffffc9000f77a338
> RBP: 0000000000000029 R08: ffffffff8a50ffb4 R09: fffffbfff24b6bd9
> R10: fffffbfff24b6bd9 R11: 0000000000000000 R12: ffff88801db73b78
> R13: fffffffffffffff9 R14: dffffc0000000000 R15: 0000000000000030
> FS: 00007f843ae8e700(0000) GS:ffff888063700000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f92ff166000 CR3: 000000003c672000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>
> Fixes: 0daf07e52709 ("raw: convert raw sockets to RCU")
> Reported-by: syzbot <syzkaller@...glegroups.com>
> Reported-by: Dae R. Jeong <threeearcat@...il.com>
> Link: https://lore.kernel.org/netdev/ZCA2mGV_cmq7lIfV@dragonet/
> Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
> ---
> include/net/raw.h | 4 ++--
> net/ipv4/raw.c | 36 +++++++++++++++++++-----------------
> net/ipv4/raw_diag.c | 10 ++++------
> net/ipv6/raw.c | 10 ++++------
> 4 files changed, 29 insertions(+), 31 deletions(-)
>
> diff --git a/include/net/raw.h b/include/net/raw.h
> index 2c004c20ed99..3af5289fdead 100644
> --- a/include/net/raw.h
> +++ b/include/net/raw.h
> @@ -37,7 +37,7 @@ int raw_rcv(struct sock *, struct sk_buff *);
> struct raw_hashinfo {
> spinlock_t lock;
>
> - struct hlist_nulls_head ht[RAW_HTABLE_SIZE] ____cacheline_aligned;
> + struct hlist_head ht[RAW_HTABLE_SIZE] ____cacheline_aligned;
> };
>
> static inline u32 raw_hashfunc(const struct net *net, u32 proto)
> @@ -51,7 +51,7 @@ static inline void raw_hashinfo_init(struct raw_hashinfo *hashinfo)
>
> spin_lock_init(&hashinfo->lock);
> for (i = 0; i < RAW_HTABLE_SIZE; i++)
> - INIT_HLIST_NULLS_HEAD(&hashinfo->ht[i], i);
> + INIT_HLIST_HEAD(&hashinfo->ht[i]);
> }
>
> #ifdef CONFIG_PROC_FS
> diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
> index 94df935ee0c5..8088a5011e7d 100644
> --- a/net/ipv4/raw.c
> +++ b/net/ipv4/raw.c
> @@ -91,12 +91,12 @@ EXPORT_SYMBOL_GPL(raw_v4_hashinfo);
> int raw_hash_sk(struct sock *sk)
> {
> struct raw_hashinfo *h = sk->sk_prot->h.raw_hash;
> - struct hlist_nulls_head *hlist;
> + struct hlist_head *hlist;
>
> hlist = &h->ht[raw_hashfunc(sock_net(sk), inet_sk(sk)->inet_num)];
>
> spin_lock(&h->lock);
> - __sk_nulls_add_node_rcu(sk, hlist);
> + sk_add_node_rcu(sk, hlist);
> sock_set_flag(sk, SOCK_RCU_FREE);
> spin_unlock(&h->lock);
> sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
> @@ -110,7 +110,7 @@ void raw_unhash_sk(struct sock *sk)
> struct raw_hashinfo *h = sk->sk_prot->h.raw_hash;
>
> spin_lock(&h->lock);
> - if (__sk_nulls_del_node_init_rcu(sk))
> + if (sk_del_node_init_rcu(sk))
> sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
> spin_unlock(&h->lock);
> }
> @@ -163,16 +163,15 @@ static int icmp_filter(const struct sock *sk, const struct sk_buff *skb)
> static int raw_v4_input(struct net *net, struct sk_buff *skb,
> const struct iphdr *iph, int hash)
> {
> - struct hlist_nulls_head *hlist;
> - struct hlist_nulls_node *hnode;
> int sdif = inet_sdif(skb);
> + struct hlist_head *hlist;
> int dif = inet_iif(skb);
> int delivered = 0;
> struct sock *sk;
>
> hlist = &raw_v4_hashinfo.ht[hash];
> rcu_read_lock();
> - sk_nulls_for_each(sk, hnode, hlist) {
> + sk_for_each_rcu(sk, hlist) {
> if (!raw_v4_match(net, sk, iph->protocol,
> iph->saddr, iph->daddr, dif, sdif))
> continue;
> @@ -264,10 +263,9 @@ static void raw_err(struct sock *sk, struct sk_buff *skb, u32 info)
> void raw_icmp_error(struct sk_buff *skb, int protocol, u32 info)
> {
> struct net *net = dev_net(skb->dev);
> - struct hlist_nulls_head *hlist;
> - struct hlist_nulls_node *hnode;
> int dif = skb->dev->ifindex;
> int sdif = inet_sdif(skb);
> + struct hlist_head *hlist;
> const struct iphdr *iph;
> struct sock *sk;
> int hash;
> @@ -276,7 +274,7 @@ void raw_icmp_error(struct sk_buff *skb, int protocol, u32 info)
> hlist = &raw_v4_hashinfo.ht[hash];
>
> rcu_read_lock();
> - sk_nulls_for_each(sk, hnode, hlist) {
> + sk_for_each_rcu(sk, hlist) {
> iph = (const struct iphdr *)skb->data;
> if (!raw_v4_match(net, sk, iph->protocol,
> iph->daddr, iph->saddr, dif, sdif))
> @@ -950,14 +948,13 @@ static struct sock *raw_get_first(struct seq_file *seq, int bucket)
> {
> struct raw_hashinfo *h = pde_data(file_inode(seq->file));
> struct raw_iter_state *state = raw_seq_private(seq);
> - struct hlist_nulls_head *hlist;
> - struct hlist_nulls_node *hnode;
> + struct hlist_head *hlist;
> struct sock *sk;
>
> for (state->bucket = bucket; state->bucket < RAW_HTABLE_SIZE;
> ++state->bucket) {
> hlist = &h->ht[state->bucket];
> - sk_nulls_for_each(sk, hnode, hlist) {
> + sk_for_each(sk, hlist) {
> if (sock_net(sk) == seq_file_net(seq))
> return sk;
> }
> @@ -970,7 +967,7 @@ static struct sock *raw_get_next(struct seq_file *seq, struct sock *sk)
> struct raw_iter_state *state = raw_seq_private(seq);
>
> do {
> - sk = sk_nulls_next(sk);
> + sk = sk_next(sk);
> } while (sk && sock_net(sk) != seq_file_net(seq));
>
> if (!sk)
> @@ -989,9 +986,12 @@ static struct sock *raw_get_idx(struct seq_file *seq, loff_t pos)
> }
>
[...]
> void *raw_seq_start(struct seq_file *seq, loff_t *pos)
> - __acquires(RCU)
> + __acquires(&h->lock)
> {
> - rcu_read_lock();
> + struct raw_hashinfo *h = pde_data(file_inode(seq->file));
> +
> + spin_lock(&h->lock);
I would like to ask two questions which make me confused:
1) Why would we use spin_lock to protect the socket in a raw hashtable
for reader's safety under the rcu protection? Normally, if we use the
RCU protection, we only make sure that we need to destroy the socket
by calling call_rcu() which would prevent the READER of the socket
from getting a NULL pointer.
2) Using spin lock when we're cating /proc/net/raw file may
block/postpone the action of hashing socket somewhere else?
Thanks,
Jason
> +
> return *pos ? raw_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
> }
> EXPORT_SYMBOL_GPL(raw_seq_start);
> @@ -1010,9 +1010,11 @@ void *raw_seq_next(struct seq_file *seq, void *v, loff_t *pos)
> EXPORT_SYMBOL_GPL(raw_seq_next);
>
> void raw_seq_stop(struct seq_file *seq, void *v)
> - __releases(RCU)
> + __releases(&h->lock)
> {
> - rcu_read_unlock();
> + struct raw_hashinfo *h = pde_data(file_inode(seq->file));
> +
> + spin_unlock(&h->lock);
> }
> EXPORT_SYMBOL_GPL(raw_seq_stop);
>
> diff --git a/net/ipv4/raw_diag.c b/net/ipv4/raw_diag.c
> index 999321834b94..da3591a66a16 100644
> --- a/net/ipv4/raw_diag.c
> +++ b/net/ipv4/raw_diag.c
> @@ -57,8 +57,7 @@ static bool raw_lookup(struct net *net, struct sock *sk,
> static struct sock *raw_sock_get(struct net *net, const struct inet_diag_req_v2 *r)
> {
> struct raw_hashinfo *hashinfo = raw_get_hashinfo(r);
> - struct hlist_nulls_head *hlist;
> - struct hlist_nulls_node *hnode;
> + struct hlist_head *hlist;
> struct sock *sk;
> int slot;
>
> @@ -68,7 +67,7 @@ static struct sock *raw_sock_get(struct net *net, const struct inet_diag_req_v2
> rcu_read_lock();
> for (slot = 0; slot < RAW_HTABLE_SIZE; slot++) {
> hlist = &hashinfo->ht[slot];
> - sk_nulls_for_each(sk, hnode, hlist) {
> + sk_for_each_rcu(sk, hlist) {
> if (raw_lookup(net, sk, r)) {
> /*
> * Grab it and keep until we fill
> @@ -142,9 +141,8 @@ static void raw_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
> struct raw_hashinfo *hashinfo = raw_get_hashinfo(r);
> struct net *net = sock_net(skb->sk);
> struct inet_diag_dump_data *cb_data;
> - struct hlist_nulls_head *hlist;
> - struct hlist_nulls_node *hnode;
> int num, s_num, slot, s_slot;
> + struct hlist_head *hlist;
> struct sock *sk = NULL;
> struct nlattr *bc;
>
> @@ -161,7 +159,7 @@ static void raw_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
> num = 0;
>
> hlist = &hashinfo->ht[slot];
> - sk_nulls_for_each(sk, hnode, hlist) {
> + sk_for_each_rcu(sk, hlist) {
> struct inet_sock *inet = inet_sk(sk);
>
> if (!net_eq(sock_net(sk), net))
> diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
> index bac9ba747bde..a327aa481df4 100644
> --- a/net/ipv6/raw.c
> +++ b/net/ipv6/raw.c
> @@ -141,10 +141,9 @@ EXPORT_SYMBOL(rawv6_mh_filter_unregister);
> static bool ipv6_raw_deliver(struct sk_buff *skb, int nexthdr)
> {
> struct net *net = dev_net(skb->dev);
> - struct hlist_nulls_head *hlist;
> - struct hlist_nulls_node *hnode;
> const struct in6_addr *saddr;
> const struct in6_addr *daddr;
> + struct hlist_head *hlist;
> struct sock *sk;
> bool delivered = false;
> __u8 hash;
> @@ -155,7 +154,7 @@ static bool ipv6_raw_deliver(struct sk_buff *skb, int nexthdr)
> hash = raw_hashfunc(net, nexthdr);
> hlist = &raw_v6_hashinfo.ht[hash];
> rcu_read_lock();
> - sk_nulls_for_each(sk, hnode, hlist) {
> + sk_for_each_rcu(sk, hlist) {
> int filtered;
>
> if (!raw_v6_match(net, sk, nexthdr, daddr, saddr,
> @@ -333,15 +332,14 @@ void raw6_icmp_error(struct sk_buff *skb, int nexthdr,
> u8 type, u8 code, int inner_offset, __be32 info)
> {
> struct net *net = dev_net(skb->dev);
> - struct hlist_nulls_head *hlist;
> - struct hlist_nulls_node *hnode;
> + struct hlist_head *hlist;
> struct sock *sk;
> int hash;
>
> hash = raw_hashfunc(net, nexthdr);
> hlist = &raw_v6_hashinfo.ht[hash];
> rcu_read_lock();
> - sk_nulls_for_each(sk, hnode, hlist) {
> + sk_for_each_rcu(sk, hlist) {
> /* Note: ipv6_hdr(skb) != skb->data */
> const struct ipv6hdr *ip6h = (const struct ipv6hdr *)skb->data;
>
> --
> 2.30.2
>
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