On 05.06.23 20:00, Mauro Carvalho Chehab wrote: > Em Mon, 5 Jun 2023 12:44:43 +0200 > Thorsten Leemhuis <regressions@xxxxxxxxxxxxx> escreveu: >> On 05.06.23 12:37, Mauro Carvalho Chehab wrote: >>> Em Mon, 5 Jun 2023 11:38:49 +0200 >>> "Linux regression tracking (Thorsten Leemhuis)" <regressions@xxxxxxxxxxxxx> escreveu: >>>> >>>> On 30.05.23 13:12, Thomas Voegtle wrote: >>>>> >>>>> I have the problem that sometimes my DVB card does not initialize >>>>> properly booting Linux 6.4-rc4. >>>>> This is not always, maybe in 3 out of 4 attempts. >>>>> When this happens somehow you don't see anything special in dmesg, but >>>>> the card just doesn't work. >>>>> >>>>> Reverting this helps: >>>>> commit 6769a0b7ee0c3b31e1b22c3fadff2bfb642de23f >>>>[...] >>>> Mauro: I wonder if this is something you or someone else has to look >>>> into, as Hyunwoo Kim posted a few times per months to Linux lists, but >>>> according to a quick search on lore hasn't posted anything since ~two >>>> months now. :-/ >>> >>> Yeah, I was slow applying this one, as I was afraid of it to cause >>> troubles. The DVB frontend state machine is complex, and uses a >>> semaphore to update its state. There was some past attempts of >>> addressing some lifetime issues there that we ended needing to revert >>> or not being applied, as the fix caused more harm than good. >>> [...] >> >> Thx for the update. That's unfortunate, but how it is sometimes. Which >> leads to a follow-up question: is reverting the culprit temporarily an >> option? Or did those old use-after-free problems became known to be a >> problem we can't live with anymore for another few months? > > Reverting the patch seems to be the way to proceed. Then, work on another > way to address UAF. > > I'm not aware of dvb users complaining about troubles due to UAF, although > it seems that there's now a CVE for it. So, maybe someone complained against > a distro Kernel, which caused the CVE to be opened. > > So, while it is nice to have the lifetime issues fixed, last time I checked, > the USB dvb-usb/dvb-usb-v2 have some logic that usually prevents it to cause > real issues during device removal, and unbinding DVB PCIe devices is > something that users don't do in practice. Thx for the explanation and handling this. I noticed you posted a revert, but it misses a fixes tag for the reverted commit and a Link: or Closes: tag to the report. I think Linus would very much welcome at least one of the latter in a situation like this (see [1] and [2]). I would, too, as then regzbot would have noticed the patch posting. But whatever, no big deal, let me tell regzbot about the latest progress manually: #regzbot monitor: https://lore.kernel.org/all/20230609082238.3671398-1-mchehab@xxxxxxxxxx/ #regzbot fix: Revert "media: dvb-core: Fix use-after-free on race condition at dvb_frontend" Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat) [1] for details, see: https://lore.kernel.org/all/CAHk-=wjMmSZzMJ3Xnskdg4+GGz=5p5p+GSYyFBTh0f-DgvdBWg@xxxxxxxxxxxxxx/ https://lore.kernel.org/all/CAHk-=wgs38ZrfPvy=nOwVkVzjpM3VFU1zobP37Fwd_h9iAD5JQ@xxxxxxxxxxxxxx/ https://lore.kernel.org/all/CAHk-=wjxzafG-=J8oT30s7upn4RhBs6TX-uVFZ5rME+L5_DoJA@xxxxxxxxxxxxxx/ [2] see Documentation/process/submitting-patches.rst (http://docs.kernel.org/process/submitting-patches.html) and Documentation/process/5.Posting.rst (https://docs.kernel.org/process/5.Posting.html) -- Everything you wanna know about Linux kernel regression tracking: https://linux-regtracking.leemhuis.info/about/#tldr If I did something stupid, please tell me, as explained on that page.
