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raw: Fix NULL deref in raw_get_next().
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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 0daf07e ("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: 0daf07e ("raw: convert raw sockets to RCU")
Reported-by: syzbot <[email protected]>
Reported-by: Dae R. Jeong <[email protected]>
Link: https://lore.kernel.org/netdev/ZCA2mGV_cmq7lIfV@dragonet/
Signed-off-by: Kuniyuki Iwashima <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Signed-off-by: Jakub Kicinski <[email protected]>
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@q2ven @kuba-moo
q2ven authored and kuba-moo committed Apr 5, 2023
1 parent 218c597 commit 0a78cf7
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Showing 4 changed files with 29 additions and 31 deletions.
4 changes: 2 additions & 2 deletions include/net/raw.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand All @@ -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
Expand Down
36 changes: 19 additions & 17 deletions net/ipv4/raw.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand All @@ -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);
}
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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;
Expand All @@ -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))
Expand Down Expand Up @@ -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;
}
Expand All @@ -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)
Expand All @@ -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);

return *pos ? raw_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
}
EXPORT_SYMBOL_GPL(raw_seq_start);
Expand All @@ -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);

Expand Down
10 changes: 4 additions & 6 deletions net/ipv4/raw_diag.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;

Expand All @@ -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
Expand Down Expand Up @@ -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;

Expand All @@ -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))
Expand Down
10 changes: 4 additions & 6 deletions net/ipv6/raw.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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,
Expand Down Expand Up @@ -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;

Expand Down

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