Messages in this thread | | | From | Saeed Mahameed <> | Subject | Re: [PATCH] net: Adding parameter detection in __ethtool_get_link_ksettings. | Date | Tue, 27 Aug 2019 19:01:41 +0000 |
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On Mon, 2019-08-26 at 17:47 +0800, Dongxu Liu wrote: > > On 8/26/19 9:23 AM, Dongxu Liu wrote: > > The __ethtool_get_link_ksettings symbol will be exported, > > and external users may use an illegal address. > > We should check the parameters before using them, > > otherwise the system will crash. > > > > [ 8980.991134] BUG: unable to handle kernel NULL pointer > > dereference at (null) > > [ 8980.993049] IP: [<ffffffff8155aca7>] > > __ethtool_get_link_ksettings+0x27/0x140 > > [ 8980.994285] PGD 0 > > [ 8980.995013] Oops: 0000 [#1] SMP > > [ 8980.995896] Modules linked in: sch_ingress ... > > [ 8981.013220] CPU: 3 PID: 25174 Comm: kworker/3:3 Tainted: > > G O ----V------- 3.10.0-327.36.58.4.x86_64 #1 > > [ 8981.017667] Workqueue: events linkwatch_event > > [ 8981.018652] task: ffff8800a8348000 ti: ffff8800b045c000 task.ti: > > ffff8800b045c000 > > [ 8981.020418] RIP: 0010:[<ffffffff8155aca7>] [<ffffffff8155aca7>] > > __ethtool_get_link_ksettings+0x27/0x140 > > [ 8981.022383] RSP: 0018:ffff8800b045fc88 EFLAGS: 00010202 > > [ 8981.023453] RAX: 0000000000000000 RBX: ffff8800b045fcac RCX: > > 0000000000000000 > > [ 8981.024726] RDX: ffff8800b658f600 RSI: ffff8800b045fcac RDI: > > ffff8802296e0000 > > [ 8981.026000] RBP: ffff8800b045fc98 R08: 0000000000000000 R09: > > 0000000000000001 > > [ 8981.027273] R10: 00000000000073e0 R11: 0000082b0cc8adea R12: > > ffff8802296e0000 > > [ 8981.028561] R13: ffff8800b566e8c0 R14: ffff8800b658f600 R15: > > ffff8800b566e000 > > [ 8981.029841] FS: 0000000000000000(0000) > > GS:ffff88023ed80000(0000) knlGS:0000000000000000 > > [ 8981.031715] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 8981.032845] CR2: 0000000000000000 CR3: 00000000b39a9000 CR4: > > 00000000003407e0 > > [ 8981.034137] DR0: 0000000000000000 DR1: 0000000000000000 DR2: > > 0000000000000000 > > [ 8981.035427] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: > > 0000000000000400 > > [ 8981.036702] Stack: > > [ 8981.037406] ffff8800b658f600 0000000000009c40 ffff8800b045fce8 > > ffffffffa047a71d > > [ 8981.039238] 000000000000004d ffff8800b045fcc8 ffff8800b045fd28 > > ffffffff815cb198 > > [ 8981.041070] ffff8800b045fcd8 ffffffff810807e6 00000000e8212951 > > 0000000000000001 > > [ 8981.042910] Call Trace: > > [ 8981.043660] [<ffffffffa047a71d>] > > bond_update_speed_duplex+0x3d/0x90 [bonding] > > [ 8981.045424] [<ffffffff815cb198>] ? inetdev_event+0x38/0x530 > > [ 8981.046554] [<ffffffff810807e6>] ? put_online_cpus+0x56/0x80 > > [ 8981.047688] [<ffffffffa0480d67>] bond_netdev_event+0x137/0x360 > > [bonding] > > ... > > > > Signed-off-by: Dongxu Liu <liudongxu3@huawei.com> > > --- > > net/core/ethtool.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/net/core/ethtool.c b/net/core/ethtool.c index > > 6288e69..9a50b64 100644 > > --- a/net/core/ethtool.c > > +++ b/net/core/ethtool.c > > @@ -545,6 +545,8 @@ int __ethtool_get_link_ksettings(struct > > net_device > > *dev, { > > ASSERT_RTNL(); > > > > + if (!dev || !dev->ethtool_ops) > > + return -EOPNOTSUPP; > > I do not believe dev can possibly be NULL at this point. > > if (!dev->ethtool_ops->get_link_ksettings) > > return -EOPNOTSUPP; > > > > > > I tried to find an appropriate Fixes: tag. > > It seems this particular bug was added either by > > Fixes: 9856909c2abb ("net: bonding: use __ethtool_get_ksettings") > > or generically in : > > Fixes: 3f1ac7a700d0 ("net: ethtool: add new ETHTOOL_xLINKSETTINGS > > API") > > In fact, "dev->ethtool_ops" is a null pointer in my environment. > I didn't get the case where "dev" is a null pointer.
dev can't be a null pointer since bond driver guarantees that and there is a check for the case where it could be null in bond_slave_netdev_event.
You can drop the "!dev" check, since also it should be the caller responsibility and we should avoid cluttering the net core code with such redundant checks.
> Maybe "if (!dev->ethtool_ops)" is more accurate for this bug. >
Also i am not sure about this, could be a bug in the device driver your enslaving.
alloc_netdev_mqs will assign &default_ethtool_ops to dev->ethtool_ops , if user provided setup callback didn't assign the driver specific ethtool_ops.
so the device driver must be doing something wrong, overwriting defult ethtool_ops with a NULL pointer maybe ? and why ?
> I found this bug in version 3.10, the function name was > __ethtool_get_settings. > After 3f1ac7a700d0 ("net: ethtool: add new ETHTOOL_xLINKSETTINGS > API"), > This function evolved into __ethtool_get_link_ksettings. >
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