Messages in this thread | | | Date | Wed, 26 Jul 2023 17:36:38 +0800 (CST) | From | "Dingyan Li" <> | Subject | Re:Re: [PATCH] USB: add usbfs ioctl to get specific superspeedplus rates |
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At 2023-07-26 16:33:22, "Oliver Neukum" <oneukum@suse.com> wrote: >On 25.07.23 18:11, Dingyan Li wrote: > >> In proc_conninfo_ex(), the number of returned bytes is determined by >> the smaller number between sizeof(struct usbdevfs_conninfo_ex) and a >> user specified size. So if we only append new members to the end of >> struct usbdevfs_conninfo_ex, it won't impact the bytes in the beginning. > >You have just caused memory corruption in user space by overwriting what >was right behind the buffer of the agreed upon size. Or, not much better, >caused a segmentation fault. > > Regards > Oliver
How come?
The actual returned bytes must be smaller than or equal to user specified size. You can check https://elixir.bootlin.com/linux/v6.5-rc3/source/drivers/usb/core/devio.c#L1493
Regards, Dingyan | |