From 7f109f7cc37108cba7243bc832988525b0d85909 Mon Sep 17 00:00:00 2001 From: Nikolay Aleksandrov Date: Sat, 21 Nov 2015 19:46:19 +0100 Subject: [PATCH] vrf: fix double free and memory corruption on register_netdevice failure When vrf's ->newlink is called, if register_netdevice() fails then it does free_netdev(), but that's also done by rtnl_newlink() so a second free happens and memory gets corrupted, to reproduce execute the following line a couple of times (1 - 5 usually is enough): $ for i in `seq 1 5`; do ip link add vrf: type vrf table 1; done; This works because we fail in register_netdevice() because of the wrong name "vrf:". And here's a trace of one crash: [ 28.792157] ------------[ cut here ]------------ [ 28.792407] kernel BUG at fs/namei.c:246! [ 28.792608] invalid opcode: 0000 [#1] SMP [ 28.793240] Modules linked in: vrf nfsd auth_rpcgss oid_registry nfs_acl nfs lockd grace sunrpc crct10dif_pclmul crc32_pclmul crc32c_intel qxl drm_kms_helper ttm drm aesni_intel aes_x86_64 psmouse glue_helper lrw evdev gf128mul i2c_piix4 ablk_helper cryptd ppdev parport_pc parport serio_raw pcspkr virtio_balloon virtio_console i2c_core acpi_cpufreq button 9pnet_virtio 9p 9pnet fscache ipv6 autofs4 ext4 crc16 mbcache jbd2 virtio_blk virtio_net sg sr_mod cdrom ata_generic ehci_pci uhci_hcd ehci_hcd e1000 usbcore usb_common ata_piix libata virtio_pci virtio_ring virtio scsi_mod floppy [ 28.796016] CPU: 0 PID: 1148 Comm: ld-linux-x86-64 Not tainted 4.4.0-rc1+ #24 [ 28.796016] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.1-20150318_183358- 04/01/2014 [ 28.796016] task: ffff8800352561c0 ti: ffff88003592c000 task.ti: ffff88003592c000 [ 28.796016] RIP: 0010:[] [] putname+0x43/0x60 [ 28.796016] RSP: 0018:ffff88003592fe88 EFLAGS: 00010246 [ 28.796016] RAX: 0000000000000000 RBX: ffff8800352561c0 RCX: 0000000000000001 [ 28.796016] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88003784f000 [ 28.796016] RBP: ffff88003592ff08 R08: 0000000000000001 R09: 0000000000000000 [ 28.796016] R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000 [ 28.796016] R13: 000000000000047c R14: ffff88003784f000 R15: ffff8800358c4a00 [ 28.796016] FS: 0000000000000000(0000) GS:ffff88003fc00000(0000) knlGS:0000000000000000 [ 28.796016] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.796016] CR2: 00007ffd583bc2d9 CR3: 0000000035a99000 CR4: 00000000000406f0 [ 28.796016] Stack: [ 28.796016] ffffffff8121045d ffffffff812102d3 ffff8800352561c0 ffff880035a91660 [ 28.796016] ffff8800008a9880 0000000000000000 ffffffff81a49940 00ffffff81218684 [ 28.796016] ffff8800352561c0 000000000000047c 0000000000000000 ffff880035b36d80 [ 28.796016] Call Trace: [ 28.796016] [] ? do_execveat_common.isra.34+0x74d/0x930 [ 28.796016] [] ? do_execveat_common.isra.34+0x5c3/0x930 [ 28.796016] [] do_execve+0x2c/0x30 [ 28.796016] [] call_usermodehelper_exec_async+0xf0/0x140 [ 28.796016] [] ? umh_complete+0x40/0x40 [ 28.796016] [] ret_from_fork+0x3f/0x70 [ 28.796016] Code: 48 8d 47 1c 48 89 e5 53 48 8b 37 48 89 fb 48 39 c6 74 1a 48 8b 3d 7e e9 8f 00 e8 49 fa fc ff 48 89 df e8 f1 01 fd ff 5b 5d f3 c3 <0f> 0b 48 89 fe 48 8b 3d 61 e9 8f 00 e8 2c fa fc ff 5b 5d eb e9 [ 28.796016] RIP [] putname+0x43/0x60 [ 28.796016] RSP Fixes: 193125dbd8eb ("net: Introduce VRF device driver") Signed-off-by: Nikolay Aleksandrov Acked-by: David Ahern Signed-off-by: David S. Miller --- drivers/net/vrf.c | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-) diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c index 92fa3e1ea65c..4f9748457f5a 100644 --- a/drivers/net/vrf.c +++ b/drivers/net/vrf.c @@ -907,7 +907,6 @@ static int vrf_newlink(struct net *src_net, struct net_device *dev, struct nlattr *tb[], struct nlattr *data[]) { struct net_vrf *vrf = netdev_priv(dev); - int err; if (!data || !data[IFLA_VRF_TABLE]) return -EINVAL; @@ -916,15 +915,7 @@ static int vrf_newlink(struct net *src_net, struct net_device *dev, dev->priv_flags |= IFF_L3MDEV_MASTER; - err = register_netdevice(dev); - if (err < 0) - goto out_fail; - - return 0; - -out_fail: - free_netdev(dev); - return err; + return register_netdevice(dev); } static size_t vrf_nl_getsize(const struct net_device *dev) -- 2.20.1