Messages in this thread | | | From | "M. Vefa Bicakci" <> | Subject | Re: [PATCH 5.8 05/85] Revert "usbip: Implement a match function to fix usbip" | Date | Thu, 8 Oct 2020 04:56:56 -0400 |
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On 07/10/2020 12.13, Greg Kroah-Hartman wrote: > On Tue, Oct 06, 2020 at 04:26:27PM +0300, M. Vefa Bicakci wrote: >> On 05/10/2020 18.26, Greg Kroah-Hartman wrote: >>> From: M. Vefa Bicakci <m.v.b@runbox.com> >>> >>> commit d6407613c1e2ef90213dee388aa16b6e1bd08cbc upstream. >>> >>> This commit reverts commit 7a2f2974f265 ("usbip: Implement a match >>> function to fix usbip"). >>> >>> In summary, commit d5643d2249b2 ("USB: Fix device driver race") >>> inadvertently broke usbip functionality, which I resolved in an incorrect >>> manner by introducing a match function to usbip, usbip_match(), that >>> unconditionally returns true. >>> >>> However, the usbip_match function, as is, causes usbip to take over >>> virtual devices used by syzkaller for USB fuzzing, which is a regression >>> reported by Andrey Konovalov. >>> >>> Furthermore, in conjunction with the fix of another bug, handled by another >>> patch titled "usbcore/driver: Fix specific driver selection" in this patch >>> set, the usbip_match function causes unexpected USB subsystem behaviour >>> when the usbip_host driver is loaded. The unexpected behaviour can be >>> qualified as follows: >>> - If commit 41160802ab8e ("USB: Simplify USB ID table match") is included >>> in the kernel, then all USB devices are bound to the usbip_host >>> driver, which appears to the user as if all USB devices were >>> disconnected. >>> - If the same commit (41160802ab8e) is not in the kernel (as is the case >>> with v5.8.10) then all USB devices are re-probed and re-bound to their >>> original device drivers, which appears to the user as a disconnection >>> and re-connection of USB devices. >>> >>> Please note that this commit will make usbip non-operational again, >>> until yet another patch in this patch set is merged, titled >>> "usbcore/driver: Accommodate usbip". >>> >>> Cc: <stable@vger.kernel.org> # 5.8: 41160802ab8e: USB: Simplify USB ID table match >>> Cc: <stable@vger.kernel.org> # 5.8 >> >> Hello Greg, >> >> Sorry for the lateness of this e-mail. >> >> I had noted commit 41160802ab8e ("USB: Simplify USB ID table match") as a >> prerequisite in the commit message, but I just realized that the commit >> identifier refers to a commit in my local git tree, and not to the actual >> commit in Linus Torvalds' git tree! I apologize for this mistake. >> >> Here is the correct commit identifier: >> 0ed9498f9ecfde50c93f3f3dd64b4cd5414d9944 ("USB: Simplify USB ID table match") >> >> Perhaps this is why the prerequisite commit was not cherry-picked to the 5.8.y >> branch. >> >> As a justification for the cherry-pick, commit 0ed9498f9ecf actually resolves >> a bug. In summary, this commit works together with commit adb6e6ac20ee ("USB: >> Also match device drivers using the ->match vfunc", which has been cherry-picked >> as part of v5.8.6) and ensures that a USB driver's ->match function is also >> called during the search for a more specialized/appropriate USB driver, in case >> the driver in question does not have an id_table. >> >> If I am to be the devil's advocate, however, then given that there is only one >> specialized USB device driver ("apple-mfi-fastcharge"), which conveniently has >> an id_table, and also given that usbip no longer has a match function, I also >> realize that it may not be crucial to cherry-pick 0ed9498f9ecf as a prerequisite >> commit. > > I'm sorry, but I don't really understand. Does 5.8.y need an additional > patch here, or is all ok because I missed the above patch?
No worries; sorry for not communicating clearly and for the delay.
I meant to state that it would be good to have commit 0ed9498f9ecf ("USB: Simplify USB ID table match") cherry picked to 5.8.y, as it fixes a bug, albeit a minor one.
Thank you,
Vefa
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