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authorEric Dumazet <edumazet@google.com>2019-10-07 12:21:05 -0700
committerJakub Kicinski <jakub.kicinski@netronome.com>2019-10-08 13:06:11 -0700
commit11fc7d5a0a2d458cae8ce5d5ee3ebfdabe2cb35a (patch)
tree18a4c9db3007476f37836f5bb0e59ff9441434e3 /drivers/net/tun.c
parentf9867b51d268d6fabcc4477d877f04aaad9299ae (diff)
downloadlinux-11fc7d5a0a2d458cae8ce5d5ee3ebfdabe2cb35a.tar.bz2
tun: fix memory leak in error path
syzbot reported a warning [1] that triggered after recent Jiri patch. This exposes a bug that we hit already in the past (see commit ff244c6b29b1 ("tun: handle register_netdevice() failures properly") for details) tun uses priv->destructor without an ndo_init() method. register_netdevice() can return an error, but will not call priv->destructor() in some cases. Jiri recent patch added one more. A long term fix would be to transfer the initialization of what we destroy in ->destructor() in the ndo_init() This looks a bit risky given the complexity of tun driver. A simpler fix is to detect after the failed register_netdevice() if the tun_free_netdev() function was called already. [1] ODEBUG: free active (active state 0) object type: timer_list hint: tun_flow_cleanup+0x0/0x280 drivers/net/tun.c:457 WARNING: CPU: 0 PID: 8653 at lib/debugobjects.c:481 debug_print_object+0x168/0x250 lib/debugobjects.c:481 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 8653 Comm: syz-executor976 Not tainted 5.4.0-rc1-next-20191004 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 panic+0x2dc/0x755 kernel/panic.c:220 __warn.cold+0x2f/0x3c kernel/panic.c:581 report_bug+0x289/0x300 lib/bug.c:195 fixup_bug arch/x86/kernel/traps.c:174 [inline] fixup_bug arch/x86/kernel/traps.c:169 [inline] do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028 RIP: 0010:debug_print_object+0x168/0x250 lib/debugobjects.c:481 Code: dd 80 b9 e6 87 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 b5 00 00 00 48 8b 14 dd 80 b9 e6 87 48 c7 c7 e0 ae e6 87 e8 80 84 ff fd <0f> 0b 83 05 e3 ee 80 06 01 48 83 c4 20 5b 41 5c 41 5d 41 5e 5d c3 RSP: 0018:ffff888095997a28 EFLAGS: 00010082 RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff815cb526 RDI: ffffed1012b32f37 RBP: ffff888095997a68 R08: ffff8880a92ac580 R09: ffffed1015d04101 R10: ffffed1015d04100 R11: ffff8880ae820807 R12: 0000000000000001 R13: ffffffff88fb5340 R14: ffffffff81627110 R15: ffff8880aa41eab8 __debug_check_no_obj_freed lib/debugobjects.c:963 [inline] debug_check_no_obj_freed+0x2d4/0x43f lib/debugobjects.c:994 kfree+0xf8/0x2c0 mm/slab.c:3755 kvfree+0x61/0x70 mm/util.c:593 netdev_freemem net/core/dev.c:9384 [inline] free_netdev+0x39d/0x450 net/core/dev.c:9533 tun_set_iff drivers/net/tun.c:2871 [inline] __tun_chr_ioctl+0x317b/0x3f30 drivers/net/tun.c:3075 tun_chr_ioctl+0x2b/0x40 drivers/net/tun.c:3355 vfs_ioctl fs/ioctl.c:47 [inline] file_ioctl fs/ioctl.c:539 [inline] do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:726 ksys_ioctl+0xab/0xd0 fs/ioctl.c:743 __do_sys_ioctl fs/ioctl.c:750 [inline] __se_sys_ioctl fs/ioctl.c:748 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:748 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x441439 Code: e8 9c ae 02 00 48 83 c4 18 c3 0f 1f 80 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 0f 83 3b 0a fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fff61c37438 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000441439 RDX: 0000000020000400 RSI: 00000000400454ca RDI: 0000000000000004 RBP: 00007fff61c37470 R08: 0000000000000001 R09: 0000000100000000 R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff R13: 0000000000000005 R14: 0000000000000000 R15: 0000000000000000 Kernel Offset: disabled Rebooting in 86400 seconds.. Fixes: ff92741270bf ("net: introduce name_node struct to be used in hashlist") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Jiri Pirko <jiri@mellanox.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Diffstat (limited to 'drivers/net/tun.c')
-rw-r--r--drivers/net/tun.c14
1 files changed, 12 insertions, 2 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 812dc3a65efb..1e541b08b136 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -2290,7 +2290,13 @@ static void tun_free_netdev(struct net_device *dev)
struct tun_struct *tun = netdev_priv(dev);
BUG_ON(!(list_empty(&tun->disabled)));
+
free_percpu(tun->pcpu_stats);
+ /* We clear pcpu_stats so that tun_set_iff() can tell if
+ * tun_free_netdev() has been called from register_netdevice().
+ */
+ tun->pcpu_stats = NULL;
+
tun_flow_uninit(tun);
security_tun_dev_free_security(tun->security);
__tun_set_ebpf(tun, &tun->steering_prog, NULL);
@@ -2859,8 +2865,12 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
err_detach:
tun_detach_all(dev);
- /* register_netdevice() already called tun_free_netdev() */
- goto err_free_dev;
+ /* We are here because register_netdevice() has failed.
+ * If register_netdevice() already called tun_free_netdev()
+ * while dealing with the error, tun->pcpu_stats has been cleared.
+ */
+ if (!tun->pcpu_stats)
+ goto err_free_dev;
err_free_flow:
tun_flow_uninit(tun);