Messages in this thread | | | Date | Tue, 2 Aug 2022 18:16:13 -0700 | From | Eric Biggers <> | Subject | Re: [PATCH v3] kernel/watch_queue: Make pipe NULL while clearing watch_queue |
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On Tue, Aug 02, 2022 at 12:19:05AM +0530, Siddh Raman Pant wrote: > On Mon, 01 Aug 2022 21:46:42 +0530 Dipanjan Das <mail.dipanjan.das@gmail.com> wrote: > > Are you referring to the reproducer attached to our original report? > > https://lore.kernel.org/all/CANX2M5bHye2ZEEhEV6PUj1kYL2KdWYeJtgXw8KZRzwrNpLYz+A@mail.gmail.com/ > > Yes, I meant the reproducer you gave. > > I suspect I must have missed CONFIG_WATCH_QUEUE=y while setting the kernel > up, extremely sorry for it. > > I now tried 5.10.y with it (using a modification of syzkaller's dashboard > config I had been using[1]), and I'm getting a __post_watch_notification() > crash (which is a related crash, as the fix[2][3] for that causes the > reproducer to not reproduce the post_one_notification crash on mainline), > but not the post_one_notification() crash you had reported. It seems if I > apply my patch, it doesn't trigger this related crash, so these bugs are > seem to be very related maybe due to racing? I haven't looked at that yet. > > I then tried on v5.10.131 since that was the exact version you had > reproduced on, and it reproduces the post_one_notification() error > successfully. Applying 353f7988dd84 causes __post_watch_notification() > crash, and then applying this v3 patch does not trigger the issue, but > the patch to fix __post_watch_notification() crash is [2], which does > not really address the issue of post_one_notification() crash which > is due to the dangling reference to a freed pipe. > > Can you please try reproducer at your end? > > Thanks, > Siddh
There were several watch_queue fixes that got merged in v5.10.134, so there's no point in testing v5.10.131. If you're still seeing a bug in the *latest* 5.10.y, then please check whether it's also present upstream. If yes, then send out a fix for it. If no, then tell stable@vger.kernel.org what commit(s) need to be backported. Please provide *full* details in each case, including any KASAN reports or other information that would help people understand the bug.
- Eric
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