On Sat, Nov 25, 2023 at 02:10:52PM +0100, Christian Brauner wrote: > On Fri, Nov 24, 2023 at 10:25:15AM -0800, Linus Torvalds wrote: > > On Fri, 24 Nov 2023 at 02:28, Christian Brauner <brauner@xxxxxxxxxx> wrote: > > > > > > * Fix a bug introduced with the iov_iter rework from last cycle. > > > > > > This broke /proc/kcore by copying too much and without the correct > > > offset. > > > > Ugh. I think the whole /proc/kcore vmalloc handling is just COMPLETELY broken. > > Ugh, I didn't even look at that closely because the fix was obviously > correct for that helper alone. Let's try and just return zeroed memory > like you suggested in your last mail before we bother fixing any of > this. > > Long-term plan, it'd be nice to just get distros to start turning > /proc/kcore off. Maybe I underestimate legitimate users but this > requires CAP_SYS_RAW_IO so it really can only be useful to pretty > privileged stuff anyway. drgn needs /proc/kcore for debugging the live kernel, which is a very important use case for lots of our users. And it does in fact read from KCORE_VMALLOC segments, which is why I found and fixed this bug. I'm happy to clean up this code, although it's a holiday weekend here so I won't get to it immediately of course. But please don't rip this out. Omar
