From: Eric Dumazet edumazet@google.com

stable inclusion from stable-v4.19.296 commit 17c75411e25a84ed25fe6bbbcf707e1068ff985c category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8MNNN CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

--------------------------------

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@googlegroups.com Signed-off-by: Eric Dumazet edumazet@google.com Cc: Steffen Klassert steffen.klassert@secunet.com Cc: Herbert Xu herbert@gondor.apana.org.au Acked-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Dong Chenchen dongchenchen2@huawei.com --- include/net/netns/xfrm.h | 1 + net/xfrm/xfrm_policy.c | 6 ++---- 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h index 9991e5ef52cc..e3775b260bb3 100644 --- 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]; diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index 8c133ecec9ab..74ce9aee28ba 100644 --- 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 *net, int dir, u32 index) 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;