| Message ID | 20191118120650.12597-1-jouni.hogander@unikie.com |
|---|---|
| State | Changes Requested |
| Delegated to: | David Miller |
| Headers | show |
| Series | [v3] net-sysfs: Fix reference count leak | expand |
On Mon, Nov 18, 2019 at 02:06:50PM +0200, jouni.hogander@unikie.com wrote: > From: Jouni Hogander <jouni.hogander@unikie.com> > > Netdev_register_kobject is calling device_initialize. In case of error > reference taken by device_initialize is not given up. > > Drivers are supposed to call free_netdev in case of error. In non-error > case the last reference is given up there and device release sequence > is triggered. In error case this reference is kept and the release > sequence is never started. > > Fix this reference count leak by allowing giving up the reference also > in error case in free_netdev. > > Also replace BUG_ON with WARN_ON in free_netdev and in netdev_release. > > This is the rootcause for couple of memory leaks reported by Syzkaller: > > BUG: memory leak unreferenced object 0xffff8880675ca008 (size 256): > comm "netdev_register", pid 281, jiffies 4294696663 (age 6.808s) > 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: > [<0000000058ca4711>] kmem_cache_alloc_trace+0x167/0x280 > [<000000002340019b>] device_add+0x882/0x1750 > [<000000001d588c3a>] netdev_register_kobject+0x128/0x380 > [<0000000011ef5535>] register_netdevice+0xa1b/0xf00 > [<000000007fcf1c99>] __tun_chr_ioctl+0x20d5/0x3dd0 > [<000000006a5b7b2b>] tun_chr_ioctl+0x2f/0x40 > [<00000000f30f834a>] do_vfs_ioctl+0x1c7/0x1510 > [<00000000fba062ea>] ksys_ioctl+0x99/0xb0 > [<00000000b1c1b8d2>] __x64_sys_ioctl+0x78/0xb0 > [<00000000984cabb9>] do_syscall_64+0x16f/0x580 > [<000000000bde033d>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [<00000000e6ca2d9f>] 0xffffffffffffffff > > BUG: memory leak > unreferenced object 0xffff8880668ba588 (size 8): > comm "kobject_set_nam", pid 286, jiffies 4294725297 (age 9.871s) > hex dump (first 8 bytes): > 6e 72 30 00 cc be df 2b nr0....+ > backtrace: > [<00000000a322332a>] __kmalloc_track_caller+0x16e/0x290 > [<00000000236fd26b>] kstrdup+0x3e/0x70 > [<00000000dd4a2815>] kstrdup_const+0x3e/0x50 > [<0000000049a377fc>] kvasprintf_const+0x10e/0x160 > [<00000000627fc711>] kobject_set_name_vargs+0x5b/0x140 > [<0000000019eeab06>] dev_set_name+0xc0/0xf0 > [<0000000069cb12bc>] netdev_register_kobject+0xc8/0x320 > [<00000000f2e83732>] register_netdevice+0xa1b/0xf00 > [<000000009e1f57cc>] __tun_chr_ioctl+0x20d5/0x3dd0 > [<000000009c560784>] tun_chr_ioctl+0x2f/0x40 > [<000000000d759e02>] do_vfs_ioctl+0x1c7/0x1510 > [<00000000351d7c31>] ksys_ioctl+0x99/0xb0 > [<000000008390040a>] __x64_sys_ioctl+0x78/0xb0 > [<0000000052d196b7>] do_syscall_64+0x16f/0x580 > [<0000000019af9236>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [<00000000bc384531>] 0xffffffffffffffff > > v2 -> v3: > * Replaced BUG_ON with WARN_ON in free_netdev and netdev_release > > v1 -> v2: > * Relying on driver calling free_netdev rather than calling > put_device directly in error path This changelog should go after "---" line. Thanks
diff --git a/net/core/dev.c b/net/core/dev.c index 99ac84ff398f..1d6c0bfb5ec5 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -9603,14 +9603,14 @@ void free_netdev(struct net_device *dev) netdev_unregister_lockdep_key(dev); - /* Compatibility with error handling in drivers */ - if (dev->reg_state == NETREG_UNINITIALIZED) { - netdev_freemem(dev); - return; - } + /* reg_state is NETREG_UNINITIALIZED if there is an error in + * registration. + */ + WARN_ON(dev->reg_state != NETREG_UNREGISTERED && + dev->reg_state != NETREG_UNINITIALIZED); - BUG_ON(dev->reg_state != NETREG_UNREGISTERED); - dev->reg_state = NETREG_RELEASED; + if (dev->reg_state != NETREG_UNINITIALIZED) + dev->reg_state = NETREG_RELEASED; /* will free via device release */ put_device(&dev->dev); diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 865ba6ca16eb..11f1e3b4b18f 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -1626,7 +1626,11 @@ static void netdev_release(struct device *d) { struct net_device *dev = to_net_dev(d); - BUG_ON(dev->reg_state != NETREG_RELEASED); + /* reg_state is NETREG_UNINITIALIZED if there is an error in + * registration. + */ + WARN_ON(dev->reg_state != NETREG_RELEASED && + dev->reg_state != NETREG_UNINITIALIZED); /* no need to wait for rcu grace period: * device is dead and about to be freed.