6.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet edumazet@google.com
[ Upstream commit dc9511dd6f37fe803f6b15b61b030728d7057417 ]
sk->sk_wmem_queued can be read locklessly from sctp_poll()
Use sk_wmem_queued_add() when the field is changed, and add READ_ONCE() annotations in sctp_writeable() and sctp_assocs_seq_show()
syzbot reported:
BUG: KCSAN: data-race in sctp_poll / sctp_wfree
read-write to 0xffff888149d77810 of 4 bytes by interrupt on cpu 0: sctp_wfree+0x170/0x4a0 net/sctp/socket.c:9147 skb_release_head_state+0xb7/0x1a0 net/core/skbuff.c:988 skb_release_all net/core/skbuff.c:1000 [inline] __kfree_skb+0x16/0x140 net/core/skbuff.c:1016 consume_skb+0x57/0x180 net/core/skbuff.c:1232 sctp_chunk_destroy net/sctp/sm_make_chunk.c:1503 [inline] sctp_chunk_put+0xcd/0x130 net/sctp/sm_make_chunk.c:1530 sctp_datamsg_put+0x29a/0x300 net/sctp/chunk.c:128 sctp_chunk_free+0x34/0x50 net/sctp/sm_make_chunk.c:1515 sctp_outq_sack+0xafa/0xd70 net/sctp/outqueue.c:1381 sctp_cmd_process_sack net/sctp/sm_sideeffect.c:834 [inline] sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1366 [inline] sctp_side_effects net/sctp/sm_sideeffect.c:1198 [inline] sctp_do_sm+0x12c7/0x31b0 net/sctp/sm_sideeffect.c:1169 sctp_assoc_bh_rcv+0x2b2/0x430 net/sctp/associola.c:1051 sctp_inq_push+0x108/0x120 net/sctp/inqueue.c:80 sctp_rcv+0x116e/0x1340 net/sctp/input.c:243 sctp6_rcv+0x25/0x40 net/sctp/ipv6.c:1120 ip6_protocol_deliver_rcu+0x92f/0xf30 net/ipv6/ip6_input.c:437 ip6_input_finish net/ipv6/ip6_input.c:482 [inline] NF_HOOK include/linux/netfilter.h:303 [inline] ip6_input+0xbd/0x1b0 net/ipv6/ip6_input.c:491 dst_input include/net/dst.h:468 [inline] ip6_rcv_finish+0x1e2/0x2e0 net/ipv6/ip6_input.c:79 NF_HOOK include/linux/netfilter.h:303 [inline] ipv6_rcv+0x74/0x150 net/ipv6/ip6_input.c:309 __netif_receive_skb_one_core net/core/dev.c:5452 [inline] __netif_receive_skb+0x90/0x1b0 net/core/dev.c:5566 process_backlog+0x21f/0x380 net/core/dev.c:5894 __napi_poll+0x60/0x3b0 net/core/dev.c:6460 napi_poll net/core/dev.c:6527 [inline] net_rx_action+0x32b/0x750 net/core/dev.c:6660 __do_softirq+0xc1/0x265 kernel/softirq.c:553 run_ksoftirqd+0x17/0x20 kernel/softirq.c:921 smpboot_thread_fn+0x30a/0x4a0 kernel/smpboot.c:164 kthread+0x1d7/0x210 kernel/kthread.c:389 ret_from_fork+0x2e/0x40 arch/x86/kernel/process.c:145 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
read to 0xffff888149d77810 of 4 bytes by task 17828 on cpu 1: sctp_writeable net/sctp/socket.c:9304 [inline] sctp_poll+0x265/0x410 net/sctp/socket.c:8671 sock_poll+0x253/0x270 net/socket.c:1374 vfs_poll include/linux/poll.h:88 [inline] do_pollfd fs/select.c:873 [inline] do_poll fs/select.c:921 [inline] do_sys_poll+0x636/0xc00 fs/select.c:1015 __do_sys_ppoll fs/select.c:1121 [inline] __se_sys_ppoll+0x1af/0x1f0 fs/select.c:1101 __x64_sys_ppoll+0x67/0x80 fs/select.c:1101 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd
value changed: 0x00019e80 -> 0x0000cc80
Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 17828 Comm: syz-executor.1 Not tainted 6.5.0-rc7-syzkaller-00185-g28f20a19294d #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot syzkaller@googlegroups.com 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://lore.kernel.org/r/20230830094519.950007-1-edumazet@google.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/sctp/proc.c | 2 +- net/sctp/socket.c | 10 +++++----- 2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/net/sctp/proc.c b/net/sctp/proc.c index f13d6a34f32f2..ec00ee75d59a6 100644 --- a/net/sctp/proc.c +++ b/net/sctp/proc.c @@ -282,7 +282,7 @@ static int sctp_assocs_seq_show(struct seq_file *seq, void *v) assoc->init_retries, assoc->shutdown_retries, assoc->rtx_data_chunks, refcount_read(&sk->sk_wmem_alloc), - sk->sk_wmem_queued, + READ_ONCE(sk->sk_wmem_queued), sk->sk_sndbuf, sk->sk_rcvbuf); seq_printf(seq, "\n"); diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 423dc400992ba..7cf207706eb66 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -69,7 +69,7 @@ #include <net/sctp/stream_sched.h>
/* Forward declarations for internal helper functions. */ -static bool sctp_writeable(struct sock *sk); +static bool sctp_writeable(const struct sock *sk); static void sctp_wfree(struct sk_buff *skb); static int sctp_wait_for_sndbuf(struct sctp_association *asoc, long *timeo_p, size_t msg_len); @@ -140,7 +140,7 @@ static inline void sctp_set_owner_w(struct sctp_chunk *chunk)
refcount_add(sizeof(struct sctp_chunk), &sk->sk_wmem_alloc); asoc->sndbuf_used += chunk->skb->truesize + sizeof(struct sctp_chunk); - sk->sk_wmem_queued += chunk->skb->truesize + sizeof(struct sctp_chunk); + sk_wmem_queued_add(sk, chunk->skb->truesize + sizeof(struct sctp_chunk)); sk_mem_charge(sk, chunk->skb->truesize); }
@@ -9144,7 +9144,7 @@ static void sctp_wfree(struct sk_buff *skb) struct sock *sk = asoc->base.sk;
sk_mem_uncharge(sk, skb->truesize); - sk->sk_wmem_queued -= skb->truesize + sizeof(struct sctp_chunk); + sk_wmem_queued_add(sk, -(skb->truesize + sizeof(struct sctp_chunk))); asoc->sndbuf_used -= skb->truesize + sizeof(struct sctp_chunk); WARN_ON(refcount_sub_and_test(sizeof(struct sctp_chunk), &sk->sk_wmem_alloc)); @@ -9299,9 +9299,9 @@ void sctp_write_space(struct sock *sk) * UDP-style sockets or TCP-style sockets, this code should work. * - Daisy */ -static bool sctp_writeable(struct sock *sk) +static bool sctp_writeable(const struct sock *sk) { - return sk->sk_sndbuf > sk->sk_wmem_queued; + return READ_ONCE(sk->sk_sndbuf) > READ_ONCE(sk->sk_wmem_queued); }
/* Wait for an association to go into ESTABLISHED state. If timeout is 0,