Re: [PATCH 4.19 24/25] uprobes: ensure that uprobe->offset and ->ref_ctr_offset are properly aligned

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Jun 10, 2020 at 04:53:06PM +0200, Oleg Nesterov wrote:
> On 06/09, Greg Kroah-Hartman wrote:
> >
> > On Wed, Jun 10, 2020 at 12:25:56AM +0530, Naresh Kamboju wrote:
> > > > @@ -911,6 +907,15 @@ static int __uprobe_register(struct inod
> > > >         if (offset > i_size_read(inode))
> > > >                 return -EINVAL;
> > > >
> > > > +       /*
> > > > +        * This ensures that copy_from_page(), copy_to_page() and
> > > > +        * __update_ref_ctr() can't cross page boundary.
> > > > +        */
> > > > +       if (!IS_ALIGNED(offset, UPROBE_SWBP_INSN_SIZE))
> > > > +               return -EINVAL;
> > > > +       if (!IS_ALIGNED(ref_ctr_offset, sizeof(short)))
> > >
> > > stable-rc 4.19 build failure for x86_64, i386 and arm.
> > > make -sk KBUILD_BUILD_USER=TuxBuild -C/linux -j16 ARCH=x86 HOSTCC=gcc
> > > CC="sccache gcc" O=build
> > >
> > > 75 #
> > > 76 In file included from ../kernel/events/uprobes.c:25:
> > > 77 ../kernel/events/uprobes.c: In function ‘__uprobe_register’:
> > > 78 ../kernel/events/uprobes.c:916:18: error: ‘ref_ctr_offset’
> > > undeclared (first use in this function); did you mean
> > > ‘per_cpu_offset’?
> > > 79  916 | if (!IS_ALIGNED(ref_ctr_offset, sizeof(short)))
> > > 80  | ^~~~~~~~~~~~~~
> > > 81 ../include/linux/kernel.h:62:30: note: in definition of macro ‘IS_ALIGNED’
> > > 82  62 | #define IS_ALIGNED(x, a) (((x) & ((typeof(x))(a) - 1)) == 0)
> > > 83  | ^
> > > 84 ../kernel/events/uprobes.c:916:18: note: each undeclared identifier
> > > is reported only once for each function it appears in
> > > 85  916 | if (!IS_ALIGNED(ref_ctr_offset, sizeof(short)))
> > > 86  | ^~~~~~~~~~~~~~
> > > 87 ../include/linux/kernel.h:62:30: note: in definition of macro ‘IS_ALIGNED’
> > > 88  62 | #define IS_ALIGNED(x, a) (((x) & ((typeof(x))(a) - 1)) == 0)
> > > 89  | ^
> > > 90 make[3]: *** [../scripts/Makefile.build:304: kernel/events/uprobes.o] Error 1
> > >
> > > --
> > > Linaro LKFT
> > > https://lkft.linaro.org
> >
> > Good catch, my builders just caught it too :(
> >
> > 4.19, 4.14, 4.9, and 4.4 are all broken, I have a fix will test it and
> > push out -rc2 for all of those with it in a bit, thanks.
> 
> Yes, SDT markers were added by 1cc33161a83d20b5462b1e93f95d3ce6388079ee in v4.20.
> 
> See the patch for v4.4 below. It changes uprobe_register(), not __uprobe_register()
> to check IS_ALIGNED(offset, UPROBE_SWBP_INSN_SIZE) only.
> 
> Greg, please let me know if you want me to send the patches for 4.9/4.14/4.19.

Please do.  I tried to backport it to those trees, and it seems to
build/boot/run, but I would like verification I didn't mess anything up
:)

Your 4.4 version below matched my version, so I think I'm ok...

thanks,

greg k-h