| Message ID | 20230908181359.1889304-1-edumazet@google.com (mailing list archive) |
|---|---|
| State | Awaiting Upstream |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] xfrm: fix a data-race in xfrm_gen_index() | expand |
On Fri, Sep 08, 2023 at 06:13:59PM +0000, Eric Dumazet wrote: > 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> > --- > include/net/netns/xfrm.h | 1 + > net/xfrm/xfrm_policy.c | 6 ++---- > 2 files changed, 3 insertions(+), 4 deletions(-) Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Thanks,
On Fri, Sep 08, 2023 at 06:13:59PM +0000, Eric Dumazet wrote: > 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> Applied, thanks a lot Eric!
diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h index bd7c3be4af5d7bee4c63a57a2b0bf283b81bc4bf..423b52eca908d90009889b64764fbd4008a29529 100644 --- a/include/net/netns/xfrm.h +++ b/include/net/netns/xfrm.h @@ -50,6 +50,7 @@ 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 d6b405782b6361c4da2e06fae50befbd699aed15..a73e4b66c98f9db98d94a146bc963fa29979c592 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -1372,8 +1372,6 @@ 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; @@ -1381,8 +1379,8 @@ 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;
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> --- include/net/netns/xfrm.h | 1 + net/xfrm/xfrm_policy.c | 6 ++---- 2 files changed, 3 insertions(+), 4 deletions(-)