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Message-ID: <CAGXu5jJx7NP+Bc4sY6ZDLwfgaoPkmAt3ohW0NikRFr_P_T=jKA@mail.gmail.com> Date: Mon, 6 Feb 2017 14:23:09 -0800 From: Kees Cook <keescook@...omium.org> To: Keun-O Park <kpark3469@...il.com> Cc: "kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>, Catalin Marinas <catalin.marinas@....com>, Will Deacon <will.deacon@....com>, Mark Rutland <mark.rutland@....com>, James Morse <james.morse@....com>, Pratyush Anand <panand@...hat.com>, keun-o.park@...kmatter.ae Subject: Re: [PATCH v3 1/3] usercopy: create enum stack_type On Sun, Feb 5, 2017 at 4:14 AM, <kpark3469@...il.com> wrote: > From: Sahara <keun-o.park@...kmatter.ae> > > This patch creates enum stack_type which is only used in usercopy.c > for now. This enum type can be used for x86 and other architecture's > thread_info.h, which may have arch_within_stack_frames(). > > Signed-off-by: Sahara <keun-o.park@...kmatter.ae> > Suggested-by: James Morse <james.morse@....com> > Reviewed-by: Kees Cook <keescook@...omium.org> Acked-by: Kees Cook <keescook@...omium.org> -Kees > --- > arch/x86/include/asm/thread_info.h | 19 ++++++++++--------- > include/linux/thread_info.h | 13 ++++++++++--- > mm/usercopy.c | 8 +------- > 3 files changed, 21 insertions(+), 19 deletions(-) > > diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h > index ad6f5eb0..7af4b8b 100644 > --- a/arch/x86/include/asm/thread_info.h > +++ b/arch/x86/include/asm/thread_info.h > @@ -168,13 +168,13 @@ static inline unsigned long current_stack_pointer(void) > * entirely contained by a single stack frame. > * > * Returns: > - * 1 if within a frame > - * -1 if placed across a frame boundary (or outside stack) > - * 0 unable to determine (no frame pointers, etc) > + * GOOD_FRAME if within a frame > + * BAD_STACK if placed across a frame boundary (or outside stack) > + * NOT_STACK unable to determine (no frame pointers, etc) > */ > -static inline int arch_within_stack_frames(const void * const stack, > - const void * const stackend, > - const void *obj, unsigned long len) > +static inline enum stack_type arch_within_stack_frames(const void * const stack, > + const void * const stackend, > + const void *obj, unsigned long len) > { > #if defined(CONFIG_FRAME_POINTER) > const void *frame = NULL; > @@ -197,13 +197,14 @@ static inline int arch_within_stack_frames(const void * const stack, > * the copy as invalid. > */ > if (obj + len <= frame) > - return obj >= oldframe + 2 * sizeof(void *) ? 1 : -1; > + return obj >= oldframe + 2 * sizeof(void *) ? > + GOOD_FRAME : BAD_STACK; > oldframe = frame; > frame = *(const void * const *)frame; > } > - return -1; > + return BAD_STACK; > #else > - return 0; > + return NOT_STACK; > #endif > } > > diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h > index 5837387..a38b3be 100644 > --- a/include/linux/thread_info.h > +++ b/include/linux/thread_info.h > @@ -22,6 +22,13 @@ > #endif > > #include <linux/bitops.h> > + > +enum stack_type { > + BAD_STACK = -1, > + NOT_STACK = 0, > + GOOD_FRAME, > + GOOD_STACK, > +}; > #include <asm/thread_info.h> > > #ifdef __KERNEL__ > @@ -77,9 +84,9 @@ static inline int test_ti_thread_flag(struct thread_info *ti, int flag) > #define tif_need_resched() test_thread_flag(TIF_NEED_RESCHED) > > #ifndef CONFIG_HAVE_ARCH_WITHIN_STACK_FRAMES > -static inline int arch_within_stack_frames(const void * const stack, > - const void * const stackend, > - const void *obj, unsigned long len) > +static inline enum stack_type arch_within_stack_frames(const void * const stack, > + const void * const stackend, > + const void *obj, unsigned long len) > { > return 0; > } > diff --git a/mm/usercopy.c b/mm/usercopy.c > index 3c8da0a..3531ae7 100644 > --- a/mm/usercopy.c > +++ b/mm/usercopy.c > @@ -16,15 +16,9 @@ > > #include <linux/mm.h> > #include <linux/slab.h> > +#include <linux/thread_info.h> > #include <asm/sections.h> > > -enum { > - BAD_STACK = -1, > - NOT_STACK = 0, > - GOOD_FRAME, > - GOOD_STACK, > -}; > - > /* > * Checks if a given pointer and length is contained by the current > * stack frame (if possible). > -- > 2.7.4 > -- Kees Cook Pixel Security
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