BUG: KASAN: slab-use-after-free in tcp_write_timer_handler+0x156/0x3e0
Read of size 1 at addr ffff888111f322cd by task swapper/0/0
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.12.0-rc4-dirty #7
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1
Call Trace:
<IRQ>
dump_stack_lvl+0x68/0xa0
print_address_description.constprop.0+0x2c/0x3d0
print_report+0xb4/0x270
kasan_report+0xbd/0xf0
tcp_write_timer_handler+0x156/0x3e0
tcp_write_timer+0x66/0x170
call_timer_fn+0xfb/0x1d0
__run_timers+0x3f8/0x480
run_timer_softirq+0x9b/0x100
handle_softirqs+0x153/0x390
__irq_exit_rcu+0x103/0x120
irq_exit_rcu+0xe/0x20
sysvec_apic_timer_interrupt+0x76/0x90
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:default_idle+0xf/0x20
Code: 4c 01 c7 4c 29 c2 e9 72 ff ff ff 90 90 90 90 90 90 90 90 90 90 90 90
90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 33 f8 25 00 fb f4 <fa> c3 cc cc cc
cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90
RSP: 0018:ffffffffa2007e28 EFLAGS: 00000242
RAX: 00000000000f3b31 RBX: 1ffffffff4400fc7 RCX: ffffffffa09c3196
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff9f00590f
RBP: 0000000000000000 R08: 0000000000000001 R09: ffffed102360835d
R10: ffff88811b041aeb R11: 0000000000000001 R12: 0000000000000000
R13: ffffffffa202d7c0 R14: 0000000000000000 R15: 00000000000147d0
default_idle_call+0x6b/0xa0
cpuidle_idle_call+0x1af/0x1f0
do_idle+0xbc/0x130
cpu_startup_entry+0x33/0x40
rest_init+0x11f/0x210
start_kernel+0x39a/0x420
x86_64_start_reservations+0x18/0x30
x86_64_start_kernel+0x97/0xa0
common_startup_64+0x13e/0x141
</TASK>
Allocated by task 595:
kasan_save_stack+0x24/0x50
kasan_save_track+0x14/0x30
__kasan_slab_alloc+0x87/0x90
kmem_cache_alloc_noprof+0x12b/0x3f0
copy_net_ns+0x94/0x380
create_new_namespaces+0x24c/0x500
unshare_nsproxy_namespaces+0x75/0xf0
ksys_unshare+0x24e/0x4f0
__x64_sys_unshare+0x1f/0x30
do_syscall_64+0x70/0x180
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Freed by task 100:
kasan_save_stack+0x24/0x50
kasan_save_track+0x14/0x30
kasan_save_free_info+0x3b/0x60
__kasan_slab_free+0x54/0x70
kmem_cache_free+0x156/0x5d0
cleanup_net+0x5d3/0x670
process_one_work+0x776/0xa90
worker_thread+0x2e2/0x560
kthread+0x1a8/0x1f0
ret_from_fork+0x34/0x60
ret_from_fork_asm+0x1a/0x30
Reproduction script:
mkdir -p /mnt/nfsshare
mkdir -p /mnt/nfs/netns_1
mkfs.ext4 /dev/sdb
mount /dev/sdb /mnt/nfsshare
systemctl restart nfs-server
chmod 777 /mnt/nfsshare
exportfs -i -o rw,no_root_squash *:/mnt/nfsshare
ip netns add netns_1
ip link add name veth_1_peer type veth peer veth_1
ifconfig veth_1_peer 11.11.0.254 up
ip link set veth_1 netns netns_1
ip netns exec netns_1 ifconfig veth_1 11.11.0.1
ip netns exec netns_1 /root/iptables -A OUTPUT -d 11.11.0.254 -p tcp \
--tcp-flags FIN FIN -j DROP
(note: In my environment, a DESTROY_CLIENTID operation is always sent
immediately, breaking the nfs tcp connection.)
ip netns exec netns_1 timeout -s 9 300 mount -t nfs -o proto=tcp,vers=4.1 \
11.11.0.254:/mnt/nfsshare /mnt/nfs/netns_1
ip netns del netns_1
The reason here is that the tcp socket in netns_1 (nfs side) has been
shutdown and closed (done in xs_destroy), but the FIN message (with ack)
is discarded, and the nfsd side keeps sending retransmission messages.
As a result, when the tcp sock in netns_1 processes the received message,
it sends the message (FIN message) in the sending queue, and the tcp timer
is re-established. When the network namespace is deleted, the net structure
accessed by tcp's timer handler function causes problems.
To fix this problem:
Add the sock_create_kern_getnet() helper function, add the get_net()
operation for the kernel socket.
Fixes: 26abe14379f8 ("net: Modify sk_alloc to not reference count the netns of kernel sockets.")
Signed-off-by: Liu Jian <liujian56@xxxxxxxxxx>
---
v1: https://lore.kernel.org/all/20241024015543.568476-1-liujian56@xxxxxxxxxx/
v1->v2: change to get netns reference count.
include/linux/net.h | 1 +
net/socket.c | 28 ++++++++++++++++++++++++++++
net/sunrpc/svcsock.c | 2 +-
net/sunrpc/xprtsock.c | 2 +-
4 files changed, 31 insertions(+), 2 deletions(-)
diff --git a/include/linux/net.h b/include/linux/net.h
index b75bc534c1b3..58216da3b62c 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -255,6 +255,7 @@ int __sock_create(struct net *net, int family, int type, int proto,
struct socket **res, int kern);
int sock_create(int family, int type, int proto, struct socket **res);
int sock_create_kern(struct net *net, int family, int type, int proto, struct socket **res);
+int sock_create_kern_getnet(struct net *net, int family, int type, int proto, struct socket **res);
int sock_create_lite(int family, int type, int proto, struct socket **res);
struct socket *sock_alloc(void);
void sock_release(struct socket *sock);
diff --git a/net/socket.c b/net/socket.c
index 042451f01c65..e64a02445b1a 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1651,6 +1651,34 @@ int sock_create_kern(struct net *net, int family, int type, int protocol, struct
}
EXPORT_SYMBOL(sock_create_kern);
+int sock_create_kern_getnet(struct net *net, int family, int type, int proto, struct socket **res)
+{
+ struct sock *sk;
+ int ret;
+
+ if (!maybe_get_net(net))
+ return -EINVAL;
+
+ ret = sock_create_kern(net, family, type, proto, res);
+ if (ret < 0) {
+ put_net(net);
+ return ret;
+ }
+
+ sk = (*res)->sk;
+ lock_sock(sk);
+ /* Update ns_tracker to current stack trace and refcounted tracker */
+ __netns_tracker_free(net, &sk->ns_tracker, false);
+
+ sk->sk_net_refcnt = 1;
+ netns_tracker_alloc(net, &sk->ns_tracker, GFP_KERNEL);
+ sock_inuse_add(net, 1);
+ release_sock(sk);
+
+ return ret;
+}
+EXPORT_SYMBOL(sock_create_kern_getnet);
+
static struct socket *__sys_socket_create(int family, int type, int protocol)
{
struct socket *sock;
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 825ec5357691..6f272013fd9b 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -1526,7 +1526,7 @@ static struct svc_xprt *svc_create_socket(struct svc_serv *serv,
return ERR_PTR(-EINVAL);
}
- error = __sock_create(net, family, type, protocol, &sock, 1);
+ error = sock_create_kern_getnet(net, family, type, protocol, &sock);
if (error < 0)
return ERR_PTR(error);
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 110749b85040..f7734ce5eec9 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1925,7 +1925,7 @@ static struct socket *xs_create_sock(struct rpc_xprt *xprt,
struct socket *sock;
int err;
- err = __sock_create(xprt->xprt_net, family, type, protocol, &sock, 1);
+ err = sock_create_kern_getnet(xprt->xprt_net, family, type, protocol, &sock);
if (err < 0) {
dprintk("RPC: can't create %d transport socket (%d).\n",
protocol, -err);
--
2.34.1
