On Sun, Jul 9, 2023 at 7:53 PM Suren Baghdasaryan <surenb@xxxxxxxxxx> wrote: > > On Sun, Jul 9, 2023 at 7:48 PM Greg Kroah-Hartman > <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > > > On Sun, Jul 09, 2023 at 09:04:09AM -0700, Suren Baghdasaryan wrote: > > > On Sun, Jul 9, 2023 at 6:32 AM Greg Kroah-Hartman > > > <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > > > > > > > On Sun, Jul 09, 2023 at 02:39:00PM +0200, Thorsten Leemhuis wrote: > > > > > On 09.07.23 13:14, Greg Kroah-Hartman wrote: > > > > > > From: Suren Baghdasaryan <surenb@xxxxxxxxxx> > > > > > > > > > > > > commit 2b4f3b4987b56365b981f44a7e843efa5b6619b9 upstream. > > > > > > > > > > > > Patch series "Avoid memory corruption caused by per-VMA locks", v4. > > > > > > > > > > > > A memory corruption was reported in [1] with bisection pointing to the > > > > > > patch [2] enabling per-VMA locks for x86. Based on the reproducer > > > > > > provided in [1] we suspect this is caused by the lack of VMA locking while > > > > > > forking a child process. > > > > > > [...] > > > > > > > > > > Question from someone that is neither a C nor a git expert -- and thus > > > > > might say something totally stupid below (and thus maybe should not have > > > > > sent this mail at all). > > > > > > > > > > But I have to wonder: is adding this patch to stable necessary given > > > > > patch 8/8? > > > > > > > > > > FWIW, this change looks like this: > > > > > > > > > > > --- > > > > > > kernel/fork.c | 6 ++++++ > > > > > > 1 file changed, 6 insertions(+) > > > > > > > > > > > > --- a/kernel/fork.c > > > > > > +++ b/kernel/fork.c > > > > > > @@ -662,6 +662,12 @@ static __latent_entropy int dup_mmap(str > > > > > > retval = -EINTR; > > > > > > goto fail_uprobe_end; > > > > > > } > > > > > > +#ifdef CONFIG_PER_VMA_LOCK > > > > > > + /* Disallow any page faults before calling flush_cache_dup_mm */ > > > > > > + for_each_vma(old_vmi, mpnt) > > > > > > + vma_start_write(mpnt); > > > > > > + vma_iter_set(&old_vmi, 0); > > > > > > +#endif > > > > > > flush_cache_dup_mm(oldmm); > > > > > > uprobe_dup_mmap(oldmm, mm); > > > > > > /* > > > > > > > > > > But when I look at kernel/fork.c in mainline I can't see this bit. I > > > > > also only see Linus' change (e.g. patch 8/8 in this series) when I look at > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/kernel/fork.c > > > > > > > > Look at 946c6b59c56d ("Merge tag 'mm-hotfixes-stable-2023-07-08-10-43' > > > > of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm") > > > > > > > > Where Linus manually dropped those #ifdefs. > > > > > > > > Hm, I'll leave them for now in 6.4.y as that is "safer", but if Suren > > > > feels comfortable, I'll gladly take a patch from him to drop them in the > > > > 6.4.y tree as well. > > > > > > Hi Greg, > > > Give me a couple hours to get back to my computer. Linus took a > > > different version of this patch and changed the description quite a > > > bit. Once I'm home I can send you the patchset that was merged into > > > his tree. Also let me know if you want to disable CONFIG_PER_VMA_LOCK > > > in the stable branch (the patch called "[PATCH 6.4 1/8] mm: disable > > > CONFIG_PER_VMA_LOCK until its fixed" which Linus did not take AFAIKT). > > > > No rush, you can do this on Monday. > > > > I took the patches that Linus added to his tree already into the stable > > 6.4.y tree, and it's in the -rc release I pushed out a few hours ago. > > I just checked your stable master branch and it's perfectly in sync > with Linus' tree. > > > > > So if you want to look at the -rc release, that would be great, the full > > list of patches can be seen here: > > https://lore.kernel.org/r/20230709111345.297026264@xxxxxxxxxxxxxxxxxxx > > Let me sync git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git > to see what's happening there. Ok, I'm looking at the linux-6.4.y branch in git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git This patch is not needed (obsolete): 32d458fa68fe ("fork: lock VMAs of the parent process when forking") Patch fb49c455323f ("fork: lock VMAs of the parent process when forking, again") can be renamed into "fork: lock VMAs of the parent process when forking" as its original. Patch 11eaf9aa0699 ("mm: disable CONFIG_PER_VMA_LOCK until its fixed") was removed in Linus' tree, see comment in 946c6b59c56dc6e7d8364a8959cb36bf6d10bc37 saying: "The merge undoes the disabling of the CONFIG_PER_VMA_LOCK feature, since it was all hopefully fixed in mainline.". Unless you want to keep CONFIG_PER_VMA_LOCK disabled in the stable tree, that patch should also be dropped. Everything else LGTM. Thanks, Suren. > Thanks, > Suren. > > > > > thanks, > > > > greg k-h
