This is a note to let you know that I've just added the patch titled
xfrm: fix a data-race in xfrm_gen_index()
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
xfrm-fix-a-data-race-in-xfrm_gen_index.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3e4bc23926b83c3c67e5f61ae8571602754131a6 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Fri, 8 Sep 2023 18:13:59 +0000
Subject: xfrm: fix a data-race in xfrm_gen_index()
From: Eric Dumazet <edumazet@xxxxxxxxxx>
commit 3e4bc23926b83c3c67e5f61ae8571602754131a6 upstream.
xfrm_gen_index() mutual exclusion uses net->xfrm.xfrm_policy_lock.
This means we must use a per-netns idx_generator variable,
instead of a static one.
Alternative would be to use an atomic variable.
syzbot reported:
BUG: KCSAN: data-race in xfrm_sk_policy_insert / xfrm_sk_policy_insert
write to 0xffffffff87005938 of 4 bytes by task 29466 on cpu 0:
xfrm_gen_index net/xfrm/xfrm_policy.c:1385 [inline]
xfrm_sk_policy_insert+0x262/0x640 net/xfrm/xfrm_policy.c:2347
xfrm_user_policy+0x413/0x540 net/xfrm/xfrm_state.c:2639
do_ipv6_setsockopt+0x1317/0x2ce0 net/ipv6/ipv6_sockglue.c:943
ipv6_setsockopt+0x57/0x130 net/ipv6/ipv6_sockglue.c:1012
rawv6_setsockopt+0x21e/0x410 net/ipv6/raw.c:1054
sock_common_setsockopt+0x61/0x70 net/core/sock.c:3697
__sys_setsockopt+0x1c9/0x230 net/socket.c:2263
__do_sys_setsockopt net/socket.c:2274 [inline]
__se_sys_setsockopt net/socket.c:2271 [inline]
__x64_sys_setsockopt+0x66/0x80 net/socket.c:2271
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
read to 0xffffffff87005938 of 4 bytes by task 29460 on cpu 1:
xfrm_sk_policy_insert+0x13e/0x640
xfrm_user_policy+0x413/0x540 net/xfrm/xfrm_state.c:2639
do_ipv6_setsockopt+0x1317/0x2ce0 net/ipv6/ipv6_sockglue.c:943
ipv6_setsockopt+0x57/0x130 net/ipv6/ipv6_sockglue.c:1012
rawv6_setsockopt+0x21e/0x410 net/ipv6/raw.c:1054
sock_common_setsockopt+0x61/0x70 net/core/sock.c:3697
__sys_setsockopt+0x1c9/0x230 net/socket.c:2263
__do_sys_setsockopt net/socket.c:2274 [inline]
__se_sys_setsockopt net/socket.c:2271 [inline]
__x64_sys_setsockopt+0x66/0x80 net/socket.c:2271
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: 0x00006ad8 -> 0x00006b18
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 29460 Comm: syz-executor.1 Not tainted 6.5.0-rc5-syzkaller-00243-g9106536c1aa3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Fixes: 1121994c803f ("netns xfrm: policy insertion in netns")
Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Acked-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/net/netns/xfrm.h | 1 +
net/xfrm/xfrm_policy.c | 6 ++----
2 files changed, 3 insertions(+), 4 deletions(-)
--- a/include/net/netns/xfrm.h
+++ b/include/net/netns/xfrm.h
@@ -48,6 +48,7 @@ struct netns_xfrm {
struct list_head policy_all;
struct hlist_head *policy_byidx;
unsigned int policy_idx_hmask;
+ unsigned int idx_generator;
struct hlist_head policy_inexact[XFRM_POLICY_MAX];
struct xfrm_policy_hash policy_bydst[XFRM_POLICY_MAX];
unsigned int policy_count[XFRM_POLICY_MAX * 2];
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -654,8 +654,6 @@ EXPORT_SYMBOL(xfrm_policy_hash_rebuild);
* of an absolute inpredictability of ordering of rules. This will not pass. */
static u32 xfrm_gen_index(struct net *net, int dir, u32 index)
{
- static u32 idx_generator;
-
for (;;) {
struct hlist_head *list;
struct xfrm_policy *p;
@@ -663,8 +661,8 @@ static u32 xfrm_gen_index(struct net *ne
int found;
if (!index) {
- idx = (idx_generator | dir);
- idx_generator += 8;
+ idx = (net->xfrm.idx_generator | dir);
+ net->xfrm.idx_generator += 8;
} else {
idx = index;
index = 0;
Patches currently in stable-queue which might be from edumazet@xxxxxxxxxx are
queue-4.19/xfrm-fix-a-data-race-in-xfrm_gen_index.patch
queue-4.19/tcp-fix-excessive-tlp-and-rack-timeouts-from-hz-rounding.patch
queue-4.19/net-nfc-fix-races-in-nfc_llcp_sock_get-and-nfc_llcp_.patch
queue-4.19/tcp-tsq-relax-tcp_small_queue_check-when-rtx-queue-contains-a-single-skb.patch
queue-4.19/xfrm-interface-use-dev_stats_inc.patch
queue-4.19/indirect-call-wrappers-helpers-to-speed-up-indirect-.patch
