Messages in this thread | | | Subject | Re: [PATCH] objtool: Documentation: document UACCESS warnings | From | Kamalesh Babulal <> | Date | Tue, 24 Mar 2020 14:11:13 +0530 |
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On 3/24/20 5:43 AM, Nick Desaulniers wrote: > Compiling with Clang and CONFIG_KASAN=y was exposing a few warnings: > call to memset() with UACCESS enabled > > Document how to fix these for future travelers. > > Link: https://github.com/ClangBuiltLinux/linux/issues/876 > Suggested-by: Peter Zijlstra <peterz@infradead.org> > Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Looks good, a minor nitpick below.
> --- > .../Documentation/stack-validation.txt | 20 +++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/tools/objtool/Documentation/stack-validation.txt b/tools/objtool/Documentation/stack-validation.txt > index de094670050b..156fee13ba02 100644 > --- a/tools/objtool/Documentation/stack-validation.txt > +++ b/tools/objtool/Documentation/stack-validation.txt > @@ -289,6 +289,26 @@ they mean, and suggestions for how to fix them. > might be corrupt due to a gcc bug. For more details, see: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70646 > > +9. file.o: warning: objtool: funcA() call to funcB() with UACCESS enabled > + > + This means that an unexpected call to a non-whitelisted function exists > + outside of arch-specific guards. > + X86: SMAP (stac/clac): __uaccess_begin()/__uaccess_end() > + ARM: PAN: uaccess_enable()/uaccess_enable() ^^^^^^ uaccess_disable()
> + > + These functions should called to denote a minimal critical section around > + access to __user variables. See also: https://lwn.net/Articles/517475/
-- Kamalesh
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