3.18.42-rt45-rc1 stable review patch. If anyone has any objections, please let me know. ------------------ From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Some time ago Sami Pietikainen reported a crash on -RT in ip_send_unicast_reply() which was later fixed by Nicholas Mc Guire (v3.12.8-rt11). Later (v3.18.8) the code was reworked and I dropped the patch. As it turns out it was mistake. I have reports that the same crash is possible with a similar backtrace. It seems that vanilla protects access to this_cpu_ptr() via local_bh_disable(). This does not work the on -RT since we can have NET_RX and NET_TX running in parallel on the same CPU. This is brings back the old locks. |Unable to handle kernel NULL pointer dereference at virtual address 00000010 |PC is at __ip_make_skb+0x198/0x3e8 |[<c04e39d8>] (__ip_make_skb) from [<c04e3ca8>] (ip_push_pending_frames+0x20/0x40) |[<c04e3ca8>] (ip_push_pending_frames) from [<c04e3ff0>] (ip_send_unicast_reply+0x210/0x22c) |[<c04e3ff0>] (ip_send_unicast_reply) from [<c04fbb54>] (tcp_v4_send_reset+0x190/0x1c0) |[<c04fbb54>] (tcp_v4_send_reset) from [<c04fcc1c>] (tcp_v4_do_rcv+0x22c/0x288) |[<c04fcc1c>] (tcp_v4_do_rcv) from [<c0474364>] (release_sock+0xb4/0x150) |[<c0474364>] (release_sock) from [<c04ed904>] (tcp_close+0x240/0x454) |[<c04ed904>] (tcp_close) from [<c0511408>] (inet_release+0x74/0x7c) |[<c0511408>] (inet_release) from [<c0470728>] (sock_release+0x30/0xb0) |[<c0470728>] (sock_release) from [<c0470abc>] (sock_close+0x1c/0x24) |[<c0470abc>] (sock_close) from [<c0115ec4>] (__fput+0xe8/0x20c) |[<c0115ec4>] (__fput) from [<c0116050>] (____fput+0x18/0x1c) |[<c0116050>] (____fput) from [<c0058138>] (task_work_run+0xa4/0xb8) |[<c0058138>] (task_work_run) from [<c0011478>] (do_work_pending+0xd0/0xe4) |[<c0011478>] (do_work_pending) from [<c000e740>] (work_pending+0xc/0x20) |Code: e3530001 8a000001 e3a00040 ea000011 (e5973010) Cc: stable-rt@xxxxxxxxxxxxxxx Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx> --- net/ipv4/tcp_ipv4.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 5d5390299277..7a9139da3854 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -62,6 +62,7 @@ #include <linux/init.h> #include <linux/times.h> #include <linux/slab.h> +#include <linux/locallock.h> #include <net/net_namespace.h> #include <net/icmp.h> @@ -562,6 +563,7 @@ void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb) } EXPORT_SYMBOL(tcp_v4_send_check); +static DEFINE_LOCAL_IRQ_LOCK(tcp_sk_lock); /* * This routine will send an RST to the other tcp. * @@ -683,10 +685,13 @@ static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb) arg.bound_dev_if = sk->sk_bound_dev_if; arg.tos = ip_hdr(skb)->tos; + + local_lock(tcp_sk_lock); ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk), skb, &TCP_SKB_CB(skb)->header.h4.opt, ip_hdr(skb)->saddr, ip_hdr(skb)->daddr, &arg, arg.iov[0].iov_len); + local_unlock(tcp_sk_lock); TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS); TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS); @@ -768,10 +773,12 @@ static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack, if (oif) arg.bound_dev_if = oif; arg.tos = tos; + local_lock(tcp_sk_lock); ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk), skb, &TCP_SKB_CB(skb)->header.h4.opt, ip_hdr(skb)->saddr, ip_hdr(skb)->daddr, &arg, arg.iov[0].iov_len); + local_unlock(tcp_sk_lock); TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS); } -- 2.8.1 -- To unsubscribe from this list: send the line "unsubscribe stable-rt" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
