On Sun, Jan 31, 2021 at 09:24:41AM -0800, Andy Lutomirski wrote: > A SMAP-violating kernel access is not a recoverable condition. Imagine > kernel code that, outside of a uaccess region, dereferences a pointer to > the user range by accident. If SMAP is on, this will reliably generate > as an intentional user access. This makes it easy for bugs to be > overlooked if code is inadequately tested both with and without SMAP. > > We discovered this because BPF can generate invalid accesses to user > memory, but those warnings only got printed if SMAP was off. With this > patch, this type of error will be discovered with SMAP on as well. > > Cc: Yonghong Song <y...@fb.com> > Cc: Dave Hansen <dave.han...@linux.intel.com> > Cc: Peter Zijlstra <pet...@infradead.org> > Cc: Alexei Starovoitov <a...@kernel.org> > Cc: Daniel Borkmann <dan...@iogearbox.net> > Signed-off-by: Andy Lutomirski <l...@kernel.org> > --- > arch/x86/mm/fault.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c > index 04cc98ec2423..d39946ad8a91 100644 > --- a/arch/x86/mm/fault.c > +++ b/arch/x86/mm/fault.c > @@ -1242,7 +1242,11 @@ void do_user_addr_fault(struct pt_regs *regs, > !(error_code & X86_PF_USER) && > !(regs->flags & X86_EFLAGS_AC))) > { ^
Might wanna fix that opening brace too. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette