| Message ID | 20191115122412.2595-1-jouni.hogander@unikie.com |
|---|---|
| State | Changes Requested |
| Delegated to: | David Miller |
| Headers | show |
| Series | net-sysfs: Fix reference count leak | expand |
On Fri, Nov 15, 2019 at 02:24:12PM +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. 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 > > Reported-by: syzbot+ad8ca40ecd77896d51e2@syzkaller.appspotmail.com > Cc: David Miller <davem@davemloft.net> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com> > Signed-off-by: Jouni Hogander <jouni.hogander@unikie.com> > --- > net/core/net-sysfs.c | 21 ++++++++++++++++----- > 1 file changed, 16 insertions(+), 5 deletions(-) > > diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c > index 865ba6ca16eb..72ecad583953 100644 > --- a/net/core/net-sysfs.c > +++ b/net/core/net-sysfs.c > @@ -1626,6 +1626,12 @@ static void netdev_release(struct device *d) > { > struct net_device *dev = to_net_dev(d); > > + /* Triggered by an error clean-up (put_device) during > + * initialization. > + */ > + if (dev->reg_state == NETREG_UNINITIALIZED) > + return; > + Are you sure about this? What about the memory involved here, what will free that? > BUG_ON(dev->reg_state != NETREG_RELEASED); > > /* no need to wait for rcu grace period: > @@ -1745,16 +1751,21 @@ int netdev_register_kobject(struct net_device *ndev) > > error = device_add(dev); > if (error) > - return error; > + goto err_device_add; > > error = register_queue_kobjects(ndev); > - if (error) { > - device_del(dev); > - return error; > - } > + if (error) > + goto err_register_queue_kobjects; > > pm_runtime_set_memalloc_noio(dev, true); > > + return error; > + > +err_register_queue_kobjects: > + device_del(dev); > +err_device_add: > + put_device(dev); > + > return error; > } > > -- > 2.17.1 The rest of the patch looks sane to me from a "uses the driver api correctly now" point of view. But I don't know the lifetime rules of the netdev structure enough to say if that check for the reg_state is correct or not. thanks, greg k-h
Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes: > On Fri, Nov 15, 2019 at 02:24:12PM +0200, jouni.hogander@unikie.com wrote: >> net/core/net-sysfs.c | 21 ++++++++++++++++----- >> 1 file changed, 16 insertions(+), 5 deletions(-) >> >> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c >> index 865ba6ca16eb..72ecad583953 100644 >> --- a/net/core/net-sysfs.c >> +++ b/net/core/net-sysfs.c >> @@ -1626,6 +1626,12 @@ static void netdev_release(struct device *d) >> { >> struct net_device *dev = to_net_dev(d); >> >> + /* Triggered by an error clean-up (put_device) during >> + * initialization. >> + */ >> + if (dev->reg_state == NETREG_UNINITIALIZED) >> + return; >> + > > Are you sure about this? What about the memory involved here, what will > free that? In net/core/dev.c:free_netdev: /* Compatibility with error handling in drivers */ if (dev->reg_state == NETREG_UNINITIALIZED) { netdev_freemem(dev); return; } I.e. driver is expected calling free_netdev in case of error and freeing of device structure is done there. This brings up the question wether put_device should be actually called in free_netdev also in error case? Maybe that would be more correct as this free_netdev exists. BR, Jouni Högander
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 865ba6ca16eb..72ecad583953 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -1626,6 +1626,12 @@ static void netdev_release(struct device *d) { struct net_device *dev = to_net_dev(d); + /* Triggered by an error clean-up (put_device) during + * initialization. + */ + if (dev->reg_state == NETREG_UNINITIALIZED) + return; + BUG_ON(dev->reg_state != NETREG_RELEASED); /* no need to wait for rcu grace period: @@ -1745,16 +1751,21 @@ int netdev_register_kobject(struct net_device *ndev) error = device_add(dev); if (error) - return error; + goto err_device_add; error = register_queue_kobjects(ndev); - if (error) { - device_del(dev); - return error; - } + if (error) + goto err_register_queue_kobjects; pm_runtime_set_memalloc_noio(dev, true); + return error; + +err_register_queue_kobjects: + device_del(dev); +err_device_add: + put_device(dev); + return error; }