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authorEric Dumazet <edumazet@google.com>2022-01-20 09:41:12 -0800
committerJakub Kicinski <kuba@kernel.org>2022-01-20 20:18:37 -0800
commitaafc2e3285c2d7a79b7ee15221c19fbeca7b1509 (patch)
tree0ee2ecc10f78c8edcb98ede05e2c22b537238299 /net
parentebdc1a0309629e71e5910b353e6b005f022ce171 (diff)
ipv6: annotate accesses to fn->fn_sernum
struct fib6_node's fn_sernum field can be read while other threads change it. Add READ_ONCE()/WRITE_ONCE() annotations. Do not change existing smp barriers in fib6_get_cookie_safe() and __fib6_update_sernum_upto_root() syzbot reported: BUG: KCSAN: data-race in fib6_clean_node / inet6_csk_route_socket write to 0xffff88813df62e2c of 4 bytes by task 1920 on cpu 1: fib6_clean_node+0xc2/0x260 net/ipv6/ip6_fib.c:2178 fib6_walk_continue+0x38e/0x430 net/ipv6/ip6_fib.c:2112 fib6_walk net/ipv6/ip6_fib.c:2160 [inline] fib6_clean_tree net/ipv6/ip6_fib.c:2240 [inline] __fib6_clean_all+0x1a9/0x2e0 net/ipv6/ip6_fib.c:2256 fib6_flush_trees+0x6c/0x80 net/ipv6/ip6_fib.c:2281 rt_genid_bump_ipv6 include/net/net_namespace.h:488 [inline] addrconf_dad_completed+0x57f/0x870 net/ipv6/addrconf.c:4230 addrconf_dad_work+0x908/0x1170 process_one_work+0x3f6/0x960 kernel/workqueue.c:2307 worker_thread+0x616/0xa70 kernel/workqueue.c:2454 kthread+0x1bf/0x1e0 kernel/kthread.c:359 ret_from_fork+0x1f/0x30 read to 0xffff88813df62e2c of 4 bytes by task 15701 on cpu 0: fib6_get_cookie_safe include/net/ip6_fib.h:285 [inline] rt6_get_cookie include/net/ip6_fib.h:306 [inline] ip6_dst_store include/net/ip6_route.h:234 [inline] inet6_csk_route_socket+0x352/0x3c0 net/ipv6/inet6_connection_sock.c:109 inet6_csk_xmit+0x91/0x1e0 net/ipv6/inet6_connection_sock.c:121 __tcp_transmit_skb+0x1323/0x1840 net/ipv4/tcp_output.c:1402 tcp_transmit_skb net/ipv4/tcp_output.c:1420 [inline] tcp_write_xmit+0x1450/0x4460 net/ipv4/tcp_output.c:2680 __tcp_push_pending_frames+0x68/0x1c0 net/ipv4/tcp_output.c:2864 tcp_push+0x2d9/0x2f0 net/ipv4/tcp.c:725 mptcp_push_release net/mptcp/protocol.c:1491 [inline] __mptcp_push_pending+0x46c/0x490 net/mptcp/protocol.c:1578 mptcp_sendmsg+0x9ec/0xa50 net/mptcp/protocol.c:1764 inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:643 sock_sendmsg_nosec net/socket.c:705 [inline] sock_sendmsg net/socket.c:725 [inline] kernel_sendmsg+0x97/0xd0 net/socket.c:745 sock_no_sendpage+0x84/0xb0 net/core/sock.c:3086 inet_sendpage+0x9d/0xc0 net/ipv4/af_inet.c:834 kernel_sendpage+0x187/0x200 net/socket.c:3492 sock_sendpage+0x5a/0x70 net/socket.c:1007 pipe_to_sendpage+0x128/0x160 fs/splice.c:364 splice_from_pipe_feed fs/splice.c:418 [inline] __splice_from_pipe+0x207/0x500 fs/splice.c:562 splice_from_pipe fs/splice.c:597 [inline] generic_splice_sendpage+0x94/0xd0 fs/splice.c:746 do_splice_from fs/splice.c:767 [inline] direct_splice_actor+0x80/0xa0 fs/splice.c:936 splice_direct_to_actor+0x345/0x650 fs/splice.c:891 do_splice_direct+0x106/0x190 fs/splice.c:979 do_sendfile+0x675/0xc40 fs/read_write.c:1245 __do_sys_sendfile64 fs/read_write.c:1310 [inline] __se_sys_sendfile64 fs/read_write.c:1296 [inline] __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1296 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae value changed: 0x0000026f -> 0x00000271 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 15701 Comm: syz-executor.2 Not tainted 5.16.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 The Fixes tag I chose is probably arbitrary, I do not think we need to backport this patch to older kernels. Fixes: c5cff8561d2d ("ipv6: add rcu grace period before freeing fib6_node") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Link: https://lore.kernel.org/r/20220120174112.1126644-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
-rw-r--r--net/ipv6/ip6_fib.c23
-rw-r--r--net/ipv6/route.c2
2 files changed, 14 insertions, 11 deletions
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 463c37dea449..413f66781e50 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -112,7 +112,7 @@ void fib6_update_sernum(struct net *net, struct fib6_info *f6i)
fn = rcu_dereference_protected(f6i->fib6_node,
lockdep_is_held(&f6i->fib6_table->tb6_lock));
if (fn)
- fn->fn_sernum = fib6_new_sernum(net);
+ WRITE_ONCE(fn->fn_sernum, fib6_new_sernum(net));
}
/*
@@ -590,12 +590,13 @@ static int fib6_dump_table(struct fib6_table *table, struct sk_buff *skb,
spin_unlock_bh(&table->tb6_lock);
if (res > 0) {
cb->args[4] = 1;
- cb->args[5] = w->root->fn_sernum;
+ cb->args[5] = READ_ONCE(w->root->fn_sernum);
}
} else {
- if (cb->args[5] != w->root->fn_sernum) {
+ int sernum = READ_ONCE(w->root->fn_sernum);
+ if (cb->args[5] != sernum) {
/* Begin at the root if the tree changed */
- cb->args[5] = w->root->fn_sernum;
+ cb->args[5] = sernum;
w->state = FWS_INIT;
w->node = w->root;
w->skip = w->count;
@@ -1345,7 +1346,7 @@ static void __fib6_update_sernum_upto_root(struct fib6_info *rt,
/* paired with smp_rmb() in fib6_get_cookie_safe() */
smp_wmb();
while (fn) {
- fn->fn_sernum = sernum;
+ WRITE_ONCE(fn->fn_sernum, sernum);
fn = rcu_dereference_protected(fn->parent,
lockdep_is_held(&rt->fib6_table->tb6_lock));
}
@@ -2174,8 +2175,8 @@ static int fib6_clean_node(struct fib6_walker *w)
};
if (c->sernum != FIB6_NO_SERNUM_CHANGE &&
- w->node->fn_sernum != c->sernum)
- w->node->fn_sernum = c->sernum;
+ READ_ONCE(w->node->fn_sernum) != c->sernum)
+ WRITE_ONCE(w->node->fn_sernum, c->sernum);
if (!c->func) {
WARN_ON_ONCE(c->sernum == FIB6_NO_SERNUM_CHANGE);
@@ -2543,7 +2544,7 @@ static void ipv6_route_seq_setup_walk(struct ipv6_route_iter *iter,
iter->w.state = FWS_INIT;
iter->w.node = iter->w.root;
iter->w.args = iter;
- iter->sernum = iter->w.root->fn_sernum;
+ iter->sernum = READ_ONCE(iter->w.root->fn_sernum);
INIT_LIST_HEAD(&iter->w.lh);
fib6_walker_link(net, &iter->w);
}
@@ -2571,8 +2572,10 @@ static struct fib6_table *ipv6_route_seq_next_table(struct fib6_table *tbl,
static void ipv6_route_check_sernum(struct ipv6_route_iter *iter)
{
- if (iter->sernum != iter->w.root->fn_sernum) {
- iter->sernum = iter->w.root->fn_sernum;
+ int sernum = READ_ONCE(iter->w.root->fn_sernum);
+
+ if (iter->sernum != sernum) {
+ iter->sernum = sernum;
iter->w.state = FWS_INIT;
iter->w.node = iter->w.root;
WARN_ON(iter->w.skip);
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index e6de94203c13..f4884cda13b9 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2802,7 +2802,7 @@ static void ip6_link_failure(struct sk_buff *skb)
if (from) {
fn = rcu_dereference(from->fib6_node);
if (fn && (rt->rt6i_flags & RTF_DEFAULT))
- fn->fn_sernum = -1;
+ WRITE_ONCE(fn->fn_sernum, -1);
}
}
rcu_read_unlock();