Excerpts from Christophe Leroy's message of August 7, 2020 3:15 am: > The verification and message introduced by commit 374f3f5979f9 > ("powerpc/mm/hash: Handle user access of kernel address gracefully") > applies to all platforms, it should not be limited to BOOK3S. > > Make the BOOK3S version of sanity_check_fault() the one for all, > and bail out earlier if not BOOK3S. > > Fixes: 374f3f5979f9 ("powerpc/mm/hash: Handle user access of kernel address > gracefully") > Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu> > --- > arch/powerpc/mm/fault.c | 8 +++----- > 1 file changed, 3 insertions(+), 5 deletions(-) > > diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c > index 925a7231abb3..2efa34d7e644 100644 > --- a/arch/powerpc/mm/fault.c > +++ b/arch/powerpc/mm/fault.c > @@ -303,7 +303,6 @@ static inline void cmo_account_page_fault(void) > static inline void cmo_account_page_fault(void) { } > #endif /* CONFIG_PPC_SMLPAR */ > > -#ifdef CONFIG_PPC_BOOK3S > static void sanity_check_fault(bool is_write, bool is_user, > unsigned long error_code, unsigned long address) > { > @@ -320,6 +319,9 @@ static void sanity_check_fault(bool is_write, bool > is_user, > return; > } > > + if (!IS_ENABLED(CONFIG_PPC_BOOK3S)) > + return;
Seems okay. Why is address == -1 special though? I guess it's because it may not be an exploit kernel reference but a buggy pointer underflow? In that case -1 doesn't seem like it would catch very much. Would it be better to test for high bit set for example ((long)address < 0) ? Anyway for your patch Reviewed-by: Nicholas Piggin <npig...@gmail.com> > + > /* > * For hash translation mode, we should never get a > * PROTFAULT. Any update to pte to reduce access will result in us > @@ -354,10 +356,6 @@ static void sanity_check_fault(bool is_write, bool > is_user, > > WARN_ON_ONCE(error_code & DSISR_PROTFAULT); > } > -#else > -static void sanity_check_fault(bool is_write, bool is_user, > - unsigned long error_code, unsigned long address) > { } > -#endif /* CONFIG_PPC_BOOK3S */ > > /* > * Define the correct "is_write" bit in error_code based > -- > 2.25.0 > >