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authorEric Dumazet <edumazet@google.com>2022-03-25 06:58:27 +0300
committerJakub Kicinski <kuba@kernel.org>2022-03-26 02:55:41 +0300
commit2d327a79ee176930dc72c131a970c891d367c1dc (patch)
tree7e0befda8321407821419c6f172e8ec79d790e7f /net/llc/af_llc.c
parent371d1ccf430903c26fb6f838473f005a31fb20b7 (diff)
downloadlinux-2d327a79ee176930dc72c131a970c891d367c1dc.tar.xz
llc: only change llc->dev when bind() succeeds
My latest patch, attempting to fix the refcount leak in a minimal way turned out to add a new bug. Whenever the bind operation fails before we attempt to grab a reference count on a device, we might release the device refcount of a prior successful bind() operation. syzbot was not happy about this [1]. Note to stable teams: Make sure commit b37a46683739 ("netdevice: add the case if dev is NULL") is already present in your trees. [1] general protection fault, probably for non-canonical address 0xdffffc0000000070: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000380-0x0000000000000387] CPU: 1 PID: 3590 Comm: syz-executor361 Tainted: G W 5.17.0-syzkaller-04796-g169e77764adc #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:llc_ui_connect+0x400/0xcb0 net/llc/af_llc.c:500 Code: 80 3c 02 00 0f 85 fc 07 00 00 4c 8b a5 38 05 00 00 48 b8 00 00 00 00 00 fc ff df 49 8d bc 24 80 03 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 a9 07 00 00 49 8b b4 24 80 03 00 00 4c 89 f2 48 RSP: 0018:ffffc900038cfcc0 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: ffff8880756eb600 RCX: 0000000000000000 RDX: 0000000000000070 RSI: ffffc900038cfe3e RDI: 0000000000000380 RBP: ffff888015ee5000 R08: 0000000000000001 R09: ffff888015ee5535 R10: ffffed1002bdcaa6 R11: 0000000000000000 R12: 0000000000000000 R13: ffffc900038cfe37 R14: ffffc900038cfe38 R15: ffff888015ee5012 FS: 0000555555acd300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020000280 CR3: 0000000077db6000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> __sys_connect_file+0x155/0x1a0 net/socket.c:1900 __sys_connect+0x161/0x190 net/socket.c:1917 __do_sys_connect net/socket.c:1927 [inline] __se_sys_connect net/socket.c:1924 [inline] __x64_sys_connect+0x6f/0xb0 net/socket.c:1924 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f016acb90b9 Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffd417947f8 EFLAGS: 00000246 ORIG_RAX: 000000000000002a RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f016acb90b9 RDX: 0000000000000010 RSI: 0000000020000140 RDI: 0000000000000003 RBP: 00007f016ac7d0a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f016ac7d130 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 </TASK> Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:llc_ui_connect+0x400/0xcb0 net/llc/af_llc.c:500 Fixes: 764f4eb6846f ("llc: fix netdevice reference leaks in llc_ui_bind()") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Cc: 赵子轩 <beraphin@gmail.com> Cc: Stoyan Manolov <smanolov@suse.de> Link: https://lore.kernel.org/r/20220325035827.360418-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/llc/af_llc.c')
-rw-r--r--net/llc/af_llc.c59
1 files changed, 34 insertions, 25 deletions
diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
index c86256064743..7f555d2e5357 100644
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -275,6 +275,7 @@ static int llc_ui_autobind(struct socket *sock, struct sockaddr_llc *addr)
{
struct sock *sk = sock->sk;
struct llc_sock *llc = llc_sk(sk);
+ struct net_device *dev = NULL;
struct llc_sap *sap;
int rc = -EINVAL;
@@ -286,16 +287,15 @@ static int llc_ui_autobind(struct socket *sock, struct sockaddr_llc *addr)
goto out;
rc = -ENODEV;
if (sk->sk_bound_dev_if) {
- llc->dev = dev_get_by_index(&init_net, sk->sk_bound_dev_if);
- if (llc->dev && addr->sllc_arphrd != llc->dev->type) {
- dev_put(llc->dev);
- llc->dev = NULL;
+ dev = dev_get_by_index(&init_net, sk->sk_bound_dev_if);
+ if (dev && addr->sllc_arphrd != dev->type) {
+ dev_put(dev);
+ dev = NULL;
}
} else
- llc->dev = dev_getfirstbyhwtype(&init_net, addr->sllc_arphrd);
- if (!llc->dev)
+ dev = dev_getfirstbyhwtype(&init_net, addr->sllc_arphrd);
+ if (!dev)
goto out;
- netdev_tracker_alloc(llc->dev, &llc->dev_tracker, GFP_KERNEL);
rc = -EUSERS;
llc->laddr.lsap = llc_ui_autoport();
if (!llc->laddr.lsap)
@@ -304,6 +304,12 @@ static int llc_ui_autobind(struct socket *sock, struct sockaddr_llc *addr)
sap = llc_sap_open(llc->laddr.lsap, NULL);
if (!sap)
goto out;
+
+ /* Note: We do not expect errors from this point. */
+ llc->dev = dev;
+ netdev_tracker_alloc(llc->dev, &llc->dev_tracker, GFP_KERNEL);
+ dev = NULL;
+
memcpy(llc->laddr.mac, llc->dev->dev_addr, IFHWADDRLEN);
memcpy(&llc->addr, addr, sizeof(llc->addr));
/* assign new connection to its SAP */
@@ -311,10 +317,7 @@ static int llc_ui_autobind(struct socket *sock, struct sockaddr_llc *addr)
sock_reset_flag(sk, SOCK_ZAPPED);
rc = 0;
out:
- if (rc) {
- dev_put_track(llc->dev, &llc->dev_tracker);
- llc->dev = NULL;
- }
+ dev_put(dev);
return rc;
}
@@ -337,6 +340,7 @@ static int llc_ui_bind(struct socket *sock, struct sockaddr *uaddr, int addrlen)
struct sockaddr_llc *addr = (struct sockaddr_llc *)uaddr;
struct sock *sk = sock->sk;
struct llc_sock *llc = llc_sk(sk);
+ struct net_device *dev = NULL;
struct llc_sap *sap;
int rc = -EINVAL;
@@ -352,25 +356,27 @@ static int llc_ui_bind(struct socket *sock, struct sockaddr *uaddr, int addrlen)
rc = -ENODEV;
rcu_read_lock();
if (sk->sk_bound_dev_if) {
- llc->dev = dev_get_by_index_rcu(&init_net, sk->sk_bound_dev_if);
- if (llc->dev) {
+ dev = dev_get_by_index_rcu(&init_net, sk->sk_bound_dev_if);
+ if (dev) {
if (is_zero_ether_addr(addr->sllc_mac))
- memcpy(addr->sllc_mac, llc->dev->dev_addr,
+ memcpy(addr->sllc_mac, dev->dev_addr,
IFHWADDRLEN);
- if (addr->sllc_arphrd != llc->dev->type ||
+ if (addr->sllc_arphrd != dev->type ||
!ether_addr_equal(addr->sllc_mac,
- llc->dev->dev_addr)) {
+ dev->dev_addr)) {
rc = -EINVAL;
- llc->dev = NULL;
+ dev = NULL;
}
}
- } else
- llc->dev = dev_getbyhwaddr_rcu(&init_net, addr->sllc_arphrd,
+ } else {
+ dev = dev_getbyhwaddr_rcu(&init_net, addr->sllc_arphrd,
addr->sllc_mac);
- dev_hold_track(llc->dev, &llc->dev_tracker, GFP_ATOMIC);
+ }
+ dev_hold(dev);
rcu_read_unlock();
- if (!llc->dev)
+ if (!dev)
goto out;
+
if (!addr->sllc_sap) {
rc = -EUSERS;
addr->sllc_sap = llc_ui_autoport();
@@ -402,6 +408,12 @@ static int llc_ui_bind(struct socket *sock, struct sockaddr *uaddr, int addrlen)
goto out_put;
}
}
+
+ /* Note: We do not expect errors from this point. */
+ llc->dev = dev;
+ netdev_tracker_alloc(llc->dev, &llc->dev_tracker, GFP_KERNEL);
+ dev = NULL;
+
llc->laddr.lsap = addr->sllc_sap;
memcpy(llc->laddr.mac, addr->sllc_mac, IFHWADDRLEN);
memcpy(&llc->addr, addr, sizeof(llc->addr));
@@ -412,10 +424,7 @@ static int llc_ui_bind(struct socket *sock, struct sockaddr *uaddr, int addrlen)
out_put:
llc_sap_put(sap);
out:
- if (rc) {
- dev_put_track(llc->dev, &llc->dev_tracker);
- llc->dev = NULL;
- }
+ dev_put(dev);
release_sock(sk);
return rc;
}