6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet edumazet@google.com
[ Upstream commit eb72e7fcc83987d5d5595b43222f23b295d5de7f ]
A lockdep report [1] with CONFIG_PROVE_RCU_LIST=y hints that sctp_v6_available() is calling dev_get_by_index_rcu() and ipv6_chk_addr() without holding rcu.
[1] ============================= WARNING: suspicious RCU usage 6.12.0-rc5-virtme #1216 Tainted: G W ----------------------------- net/core/dev.c:876 RCU-list traversed in non-reader section!!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1 1 lock held by sctp_hello/31495: #0: ffff9f1ebbdb7418 (sk_lock-AF_INET6){+.+.}-{0:0}, at: sctp_bind (./arch/x86/include/asm/jump_label.h:27 net/sctp/socket.c:315) sctp
stack backtrace: CPU: 7 UID: 0 PID: 31495 Comm: sctp_hello Tainted: G W 6.12.0-rc5-virtme #1216 Tainted: [W]=WARN Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: <TASK> dump_stack_lvl (lib/dump_stack.c:123) lockdep_rcu_suspicious (kernel/locking/lockdep.c:6822) dev_get_by_index_rcu (net/core/dev.c:876 (discriminator 7)) sctp_v6_available (net/sctp/ipv6.c:701) sctp sctp_do_bind (net/sctp/socket.c:400 (discriminator 1)) sctp sctp_bind (net/sctp/socket.c:320) sctp inet6_bind_sk (net/ipv6/af_inet6.c:465) ? security_socket_bind (security/security.c:4581 (discriminator 1)) __sys_bind (net/socket.c:1848 net/socket.c:1869) ? do_user_addr_fault (./include/linux/rcupdate.h:347 ./include/linux/rcupdate.h:880 ./include/linux/mm.h:729 arch/x86/mm/fault.c:1340) ? do_user_addr_fault (./arch/x86/include/asm/preempt.h:84 (discriminator 13) ./include/linux/rcupdate.h:98 (discriminator 13) ./include/linux/rcupdate.h:882 (discriminator 13) ./include/linux/mm.h:729 (discriminator 13) arch/x86/mm/fault.c:1340 (discriminator 13)) __x64_sys_bind (net/socket.c:1877 (discriminator 1) net/socket.c:1875 (discriminator 1) net/socket.c:1875 (discriminator 1)) do_syscall_64 (arch/x86/entry/common.c:52 (discriminator 1) arch/x86/entry/common.c:83 (discriminator 1)) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) RIP: 0033:0x7f59b934a1e7 Code: 44 00 00 48 8b 15 39 8c 0c 00 f7 d8 64 89 02 b8 ff ff ff ff eb bd 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 b8 31 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 09 8c 0c 00 f7 d8 64 89 01 48 All code ======== 0: 44 00 00 add %r8b,(%rax) 3: 48 8b 15 39 8c 0c 00 mov 0xc8c39(%rip),%rdx # 0xc8c43 a: f7 d8 neg %eax c: 64 89 02 mov %eax,%fs:(%rdx) f: b8 ff ff ff ff mov $0xffffffff,%eax 14: eb bd jmp 0xffffffffffffffd3 16: 66 2e 0f 1f 84 00 00 cs nopw 0x0(%rax,%rax,1) 1d: 00 00 00 20: 0f 1f 00 nopl (%rax) 23: b8 31 00 00 00 mov $0x31,%eax 28: 0f 05 syscall 2a:* 48 3d 01 f0 ff ff cmp $0xfffffffffffff001,%rax <-- trapping instruction 30: 73 01 jae 0x33 32: c3 ret 33: 48 8b 0d 09 8c 0c 00 mov 0xc8c09(%rip),%rcx # 0xc8c43 3a: f7 d8 neg %eax 3c: 64 89 01 mov %eax,%fs:(%rcx) 3f: 48 rex.W
Code starting with the faulting instruction =========================================== 0: 48 3d 01 f0 ff ff cmp $0xfffffffffffff001,%rax 6: 73 01 jae 0x9 8: c3 ret 9: 48 8b 0d 09 8c 0c 00 mov 0xc8c09(%rip),%rcx # 0xc8c19 10: f7 d8 neg %eax 12: 64 89 01 mov %eax,%fs:(%rcx) 15: 48 rex.W RSP: 002b:00007ffe2d0ad398 EFLAGS: 00000202 ORIG_RAX: 0000000000000031 RAX: ffffffffffffffda RBX: 00007ffe2d0ad3d0 RCX: 00007f59b934a1e7 RDX: 000000000000001c RSI: 00007ffe2d0ad3d0 RDI: 0000000000000005 RBP: 0000000000000005 R08: 1999999999999999 R09: 0000000000000000 R10: 00007f59b9253298 R11: 0000000000000202 R12: 00007ffe2d0ada61 R13: 0000000000000000 R14: 0000562926516dd8 R15: 00007f59b9479000 </TASK>
Fixes: 6fe1e52490a9 ("sctp: check ipv6 addr with sk_bound_dev if set") Signed-off-by: Eric Dumazet edumazet@google.com Cc: Marcelo Ricardo Leitner marcelo.leitner@gmail.com Acked-by: Xin Long lucien.xin@gmail.com Link: https://patch.msgid.link/20241107192021.2579789-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/sctp/ipv6.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c index 43f2731bf590e..08acda9ecdf56 100644 --- a/net/sctp/ipv6.c +++ b/net/sctp/ipv6.c @@ -684,7 +684,7 @@ static int sctp_v6_available(union sctp_addr *addr, struct sctp_sock *sp) struct sock *sk = &sp->inet.sk; struct net *net = sock_net(sk); struct net_device *dev = NULL; - int type; + int type, res, bound_dev_if;
type = ipv6_addr_type(in6); if (IPV6_ADDR_ANY == type) @@ -698,14 +698,21 @@ static int sctp_v6_available(union sctp_addr *addr, struct sctp_sock *sp) if (!(type & IPV6_ADDR_UNICAST)) return 0;
- if (sk->sk_bound_dev_if) { - dev = dev_get_by_index_rcu(net, sk->sk_bound_dev_if); + rcu_read_lock(); + bound_dev_if = READ_ONCE(sk->sk_bound_dev_if); + if (bound_dev_if) { + res = 0; + dev = dev_get_by_index_rcu(net, bound_dev_if); if (!dev) - return 0; + goto out; }
- return ipv6_can_nonlocal_bind(net, &sp->inet) || - ipv6_chk_addr(net, in6, dev, 0); + res = ipv6_can_nonlocal_bind(net, &sp->inet) || + ipv6_chk_addr(net, in6, dev, 0); + +out: + rcu_read_unlock(); + return res; }
/* This function checks if the address is a valid address to be used for