Messages in this thread Patch in this message | | | Date | Sat, 8 Feb 2020 00:55:10 -0800 | From | Kees Cook <> | Subject | Re: [PATCH] ARM: rename missed uaccess .fixup section |
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On Sat, Feb 08, 2020 at 07:54:39AM +0000, Ard Biesheuvel wrote: > On Sat, 8 Feb 2020 at 02:02, Kees Cook <keescook@chromium.org> wrote: > > > > When the uaccess .fixup section was renamed to .text.fixup, one case was > > missed. Under ld.bfd, the orphaned section was moved close to .text > > (since they share the "ax" bits), so things would work normally on > > uaccess faults. Under ld.lld, the orphaned section was placed outside > > the .text section, making it unreachable. Rename the missed section. > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/282 > > Link: https://bugs.chromium.org/p/chromium/issues/detail?id=1020633#c44 > > Link: https://lore.kernel.org/r/nycvar.YSQ.7.76.1912032147340.17114@knanqh.ubzr > > Fixes: c4a84ae39b4a5 ("ARM: 8322/1: keep .text and .fixup regions closer together") > > Cc: stable@vger.kernel.org > > Reported-by: Nathan Chancellor <natechancellor@gmail.com> > > Reported-by: Manoj Gupta <manojgupta@google.com> > > Debugged-by: Nick Desaulniers <ndesaulniers@google.com> > > Signed-off-by: Kees Cook <keescook@chromium.org> > > Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Thanks!
> As Nick points out, the *(.fixup) line still appears in the > decompressor's linker script, but this is harmless, given that we > don't ever emit anything into that section. But while we're at it, we > might just remove it as well.
Agreed. I'll send a separate patch for that.
-Kees
> > > > --- > > I completely missed this the first several times I looked at this > > problem. Thank you Nicolas for pushing back on the earlier patch! > > Manoj or Nathan, can you test this? > > --- > > arch/arm/lib/copy_from_user.S | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/arm/lib/copy_from_user.S b/arch/arm/lib/copy_from_user.S > > index 95b2e1ce559c..f8016e3db65d 100644 > > --- a/arch/arm/lib/copy_from_user.S > > +++ b/arch/arm/lib/copy_from_user.S > > @@ -118,7 +118,7 @@ ENTRY(arm_copy_from_user) > > > > ENDPROC(arm_copy_from_user) > > > > - .pushsection .fixup,"ax" > > + .pushsection .text.fixup,"ax" > > .align 0 > > copy_abort_preamble > > ldmfd sp!, {r1, r2, r3} > > -- > > 2.20.1 > > > > > > -- > > Kees Cook
-- Kees Cook
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