On Fri, Mar 8, 2019 at 1:31 AM maowenan <maowe...@huawei.com> wrote: > On 2019/3/8 4:36, Paul Moore wrote: > > On Wed, Mar 6, 2019 at 9:44 PM Mao Wenan <maowe...@huawei.com> wrote: > >> > >> If netlbl_sock_setattr() is failed, it directly returns rc and forgets > >> to free secattr. > >> > >> BUG: memory leak > >> unreferenced object 0xffff8883c3ea4200 (size 2664): > >> comm "syz-executor.2", pid 8813, jiffies 4297264419 (age 156.090s) > >> hex dump (first 32 bytes): > >> 7f 00 00 01 7f 00 00 01 eb 7f ed 71 4e 24 00 00 ...........qN$.. > >> 02 00 07 40 00 00 00 00 00 00 00 00 00 00 00 00 ...@............ > >> backtrace: > >> [<000000004c0228da>] sk_alloc+0x3d/0xc00 net/core/sock.c:1523 > >> [<00000000535a3da2>] inet_create+0x339/0xe10 net/ipv4/af_inet.c:321 > >> [<000000009aec3cfe>] __sock_create+0x3fa/0x790 net/socket.c:1275 > >> [<000000004274b384>] sock_create net/socket.c:1315 [inline] > >> [<000000004274b384>] __sys_socket+0xe7/0x1d0 net/socket.c:1345 > >> [<00000000b3fdc826>] __do_sys_socket net/socket.c:1354 [inline] > >> [<00000000b3fdc826>] __se_sys_socket net/socket.c:1352 [inline] > >> [<00000000b3fdc826>] __x64_sys_socket+0x74/0xb0 net/socket.c:1352 > >> [<000000004ae3186e>] do_syscall_64+0xc8/0x580 > >> arch/x86/entry/common.c:290 > >> [<00000000bc0d2230>] entry_SYSCALL_64_after_hwframe+0x49/0xbe > >> [<00000000f737e62f>] 0xffffffffffffffff > >> > >> BUG: memory leak > >> unreferenced object 0xffff8883de23d570 (size 32): > >> comm "syz-executor.2", pid 8813, jiffies 4297264419 (age 156.090s) > >> hex dump (first 32 bytes): > >> 02 00 00 00 00 00 00 00 60 a9 40 ce 83 88 ff ff ........`.@..... > >> 01 00 00 00 03 00 00 00 10 00 00 00 00 00 00 00 ................ > >> backtrace: > >> [<0000000035ba8b75>] security_sk_alloc+0x5e/0xb0 > >> security/security.c:1473 > >> [<00000000302cc426>] sk_prot_alloc+0x8e/0x290 net/core/sock.c:1472 > >> [<000000004c0228da>] sk_alloc+0x3d/0xc00 net/core/sock.c:1523 > >> [<00000000535a3da2>] inet_create+0x339/0xe10 net/ipv4/af_inet.c:321 > >> [<000000009aec3cfe>] __sock_create+0x3fa/0x790 net/socket.c:1275 > >> [<000000004274b384>] sock_create net/socket.c:1315 [inline] > >> [<000000004274b384>] __sys_socket+0xe7/0x1d0 net/socket.c:1345 > >> [<00000000b3fdc826>] __do_sys_socket net/socket.c:1354 [inline] > >> [<00000000b3fdc826>] __se_sys_socket net/socket.c:1352 [inline] > >> [<00000000b3fdc826>] __x64_sys_socket+0x74/0xb0 net/socket.c:1352 > >> [<000000004ae3186e>] do_syscall_64+0xc8/0x580 > >> arch/x86/entry/common.c:290 > >> [<00000000bc0d2230>] entry_SYSCALL_64_after_hwframe+0x49/0xbe > >> [<00000000f737e62f>] 0xffffffffffffffff > >> > >> BUG: memory leak > >> unreferenced object 0xffff8883ce40a960 (size 64): > >> comm "syz-executor.2", pid 8813, jiffies 4297264420 (age 156.089s) > >> hex dump (first 32 bytes): > >> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > >> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > >> backtrace: > >> [<0000000029add401>] selinux_netlbl_socket_post_create+0x68/0x130 > >> security/selinux/netlabel.c:416 > >> [<000000005368a19c>] selinux_socket_post_create+0x31a/0x7f0 > >> security/selinux/hooks.c:4597 > >> [<00000000bd4730e2>] security_socket_post_create+0x70/0xc0 > >> security/security.c:1385 > >> [<00000000671052a4>] __sock_create+0x5a6/0x790 net/socket.c:1291 > >> [<000000004274b384>] sock_create net/socket.c:1315 [inline] > >> [<000000004274b384>] __sys_socket+0xe7/0x1d0 net/socket.c:1345 > >> [<00000000b3fdc826>] __do_sys_socket net/socket.c:1354 [inline] > >> [<00000000b3fdc826>] __se_sys_socket net/socket.c:1352 [inline] > >> [<00000000b3fdc826>] __x64_sys_socket+0x74/0xb0 net/socket.c:1352 > >> [<000000004ae3186e>] do_syscall_64+0xc8/0x580 > >> arch/x86/entry/common.c:290 > >> [<00000000bc0d2230>] entry_SYSCALL_64_after_hwframe+0x49/0xbe > >> [<00000000f737e62f>] 0xffffffffffffffff > >> > >> Fixes: 389fb800ac8b("netlabel: Label incoming TCP connections correctly in > >> SELinux") > >> Reported-by: Hulk Robot <hul...@huawei.com> > >> Signed-off-by: Mao Wenan <maowe...@huawei.com> > >> --- > >> security/selinux/netlabel.c | 3 +++ > >> 1 file changed, 3 insertions(+) > >> > >> diff --git a/security/selinux/netlabel.c b/security/selinux/netlabel.c > >> index 186e727b737b..f3da05338580 100644 > >> --- a/security/selinux/netlabel.c > >> +++ b/security/selinux/netlabel.c > >> @@ -426,6 +426,9 @@ int selinux_netlbl_socket_post_create(struct sock *sk, > >> u16 family) > >> rc = 0; > >> break; > >> } > >> + if (rc != 0) { > >> + netlbl_secattr_free(secattr); > >> + } > > > > This is likely going to cause a problem as the > > sock->sk_security->nlbl_secattr still has a reference to the secattr > > pointer you are releasing here. Assuming things are working correctly > > elsewhere, I believe freeing secattr here will result in a double free > > when the network stacks cleans up after the failed socket creation > > (via the sock_release() call in the error handling code). > Do you mean here? > err = security_socket_post_create(sock, family, type, protocol, kern); > if (err) > goto out_sock_release; > ... > > out_sock_release: > sock_release(sock); > return err; > yes, the call trace may like below: > > sock_release->__sock_release->inet_release->tcp_close->sock_put->sk_free->__sk_free->sk_destruct-> > > __sk_destruct->sk_prot_free->security_sk_free->selinux_sk_free_security->selinux_netlbl_sk_security_free-> > netlbl_secattr_free > > so, it is no need to free in selinux_netlbl_socket_post_create(). > Please correct me if this is incorrect.
I haven't followed the entirely call stack lately, but that looks right. > > It looks like you may have found this via a test tool (syzbot?), do > > you have a reproducer you can share? > > The issue has been found by syzkaller, but unfortunately it is no reproducer, > it is > only some backtrace. If you are able to reproduce this please let us know, it may be a sign that something is wrong with the LSM hooks. Thanks. -- paul moore www.paul-moore.com