Messages in this thread | | | From | YE Chengfeng <> | Subject | 回复: drivers/char: suspected null-pointer de reference problem in handle control message | Date | Tue, 26 Oct 2021 11:51:37 +0000 |
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Thanks for your reply.
Agree with you, seems that the branch at #line 1573 already handles this situation.
Another question, is it possible that port->name is null when show_port_name is invoked? I don't see any null-check there, could it be a null-dereference problem at #line 1282? Link is below. https://github.com/torvalds/linux/blob/master/drivers/char/virtio_console.c#L1282
Best Regards. Chengfeng -----邮件原件----- 发件人: Amit Shah <amit@infradead.org> 发送时间: 2021年10月26日 18:30 收件人: YE Chengfeng <cyeaa@connect.ust.hk>; amit@kernel.org; arnd@arndb.de; linux-kernel@vger.kernel.org 主题: Re: drivers/char: suspected null-pointer dereference problem in handle_control_message
On Tue, 2021-10-26 at 06:17 +0000, YE Chengfeng wrote: > Hi, > > https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgith > ub.com%2Ftorvalds%2Flinux%2Fblob%2Fmaster%2Fdrivers%2Fchar%2Fvirtio_co > nsole.c%23L1657&data=04%7C01%7Ccyeaa%40connect.ust.hk%7Ccfdf9c167c > 6749fe336a08d9986ba318%7C6c1d415239d044ca88d9b8d6ddca0708%7C1%7C0%7C63 > 7708410345384834%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV > 2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=GBDIMmW7FA1kawm > SoKAH7xTW92%2BrHMo2i2SVR42XFqE%3D&reserved=0 > > Our experimental static analysis tool detects a suspected null-pointer-dereference problem. We manually check it, but It still could be false positive because we are not familiar with the code. We report this to you just in case. > > We notice that in some branches of switch case at line #1582, the pointer port is null check. But null check is missing at line #1657 and line #1633. It seems like a suspected null-pointer dereference pointer. Would you like to spare some time to have a look at it?
For this NULL deref to happen, the host will have to send a port_name command before a port_add command. Worrying about that isn't worthwhile. If you'd like to add a generic `if (unlikely(!port))` after line 1579 there, that'd be fine as a hint to the static analysis tools, though, so just for that reason, it might be worthwhile.
Amit
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