Le 14/12/2022 à 05:42, Nicholas Miehlbradt a écrit :
> Walks the stack when copy_{to,from}_user address is in the stack to
> ensure that the object being copied is entirely within a single stack
> frame.
>
> Substatially similar to the x86 implementation except using the back
> chain to traverse the stack and identify stack frame boundaries.
>
> Signed-off-by: Nicholas Miehlbradt <nicho...@linux.ibm.com>
> ---
> arch/powerpc/Kconfig | 1 +
> arch/powerpc/include/asm/thread_info.h | 38 ++++++++++++++++++++++++++
> 2 files changed, 39 insertions(+)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 2ca5418457ed..4c59d139ea83 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -198,6 +198,7 @@ config PPC
> select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN
> select HAVE_ARCH_KFENCE if ARCH_SUPPORTS_DEBUG_PAGEALLOC
> select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
> + select HAVE_ARCH_WITHIN_STACK_FRAMES if PPC64
Why don't you do something that works for both PPC32 and PPC64 ?
> select HAVE_ARCH_KGDB
> select HAVE_ARCH_MMAP_RND_BITS
> select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
> diff --git a/arch/powerpc/include/asm/thread_info.h
> b/arch/powerpc/include/asm/thread_info.h
> index af58f1ed3952..efdf39e07884 100644
> --- a/arch/powerpc/include/asm/thread_info.h
> +++ b/arch/powerpc/include/asm/thread_info.h
> @@ -186,6 +186,44 @@ static inline bool test_thread_local_flags(unsigned int
> flags)
> #define is_elf2_task() (0)
> #endif
>
> +#ifdef CONFIG_PPC64
> +
> +#ifdef CONFIG_PPC64_ELF_ABI_V1
> +#define PARAMETER_SAVE_OFFSET 48
> +#else
> +#define PARAMETER_SAVE_OFFSET 32
> +#endif
Why not use STACK_INT_FRAME_REGS, defined in asm/ptrace.h ?
> +
> +/*
> + * Walks up the stack frames to make sure that the specified object is
> + * entirely contained by a single stack frame.
> + *
> + * Returns:
> + * GOOD_FRAME if within a frame
> + * BAD_STACK if placed across a frame boundary (or outside stack)
> + */
> +static inline int arch_within_stack_frames(const void * const stack,
> + const void * const stackend,
> + const void *obj, unsigned long len)
> +{
> + const void *frame;
> + const void *oldframe;
> +
> + oldframe = (const void *)current_stack_pointer;
> + frame = *(const void * const *)oldframe;
> +
> + while (stack <= frame && frame < stackend) {
> + if (obj + len <= frame)
> + return obj >= oldframe + PARAMETER_SAVE_OFFSET ?
> + GOOD_FRAME : BAD_STACK;
> + oldframe = frame;
> + frame = *(const void * const *)oldframe;
> + }
> +
> + return BAD_STACK;
> +}
What about:
+ const void *frame;
+ const void *params;
+
+ params = (const void *)current_stack_pointer + STACK_INT_FRAME_REGS;
+ frame = *(const void * const *)current_stack_pointer;
+
+ while (stack <= frame && frame < stackend) {
+ if (obj + len <= frame)
+ return obj >= params ? GOOD_FRAME : BAD_STACK;
+ params = frame + STACK_INT_FRAME_REGS;
+ frame = *(const void * const *)frame;
+ }
+
+ return BAD_STACK;
> +#endif /* CONFIG_PPC64 */
> +
> #endif /* !__ASSEMBLY__ */
>
> #endif /* __KERNEL__ */
