Messages in this thread |  | | Date | Fri, 14 Oct 2016 12:25:57 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v3] kprobes: unpoison stack in jprobe_return() for KASAN |
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On Fri, Oct 14, 2016 at 12:53:56PM +0200, Dmitry Vyukov wrote: > KASAN stack instrumentation poisons stack redzones on function entry > and unpoisons them on function exit. If a function exits abnormally > (e.g. with a longjmp like jprobe_return()), stack redzones are left > poisoned. Later this leads to random KASAN false reports. > > Unpoison stack redzones in the frames we are going to jump over > before doing actual longjmp in jprobe_return(). > > Signed-off-by: Dmitry Vyukov <dvyukov@google.com> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> > Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> > Cc: Alexander Potapenko <glider@google.com> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Ingo Molnar <mingo@kernel.org> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: "H. Peter Anvin" <hpa@zytor.com> > Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com> > Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> > Cc: "David S. Miller" <davem@davemloft.net> > Cc: Masami Hiramatsu <mhiramat@kernel.org> > Cc: x86@kernel.org > Cc: kasan-dev@googlegroups.com > > -- > > Changes since v1: > - leave kasan_unpoison_remaining_stack() intact > - instead add kasan_unpoison_stack_above_sp_to() > - rename kasan_unpoison_remaining_stack() to kasan_unpoison_task_stack_below() > > Changes since v2: > - fix build by adding return type to kasan_unpoison_stack_above_sp_to > (tested v2 with it, but forgot to git add)
I get build warnings with this patch applied and KASAN enabled:
mm/kasan/kasan.c: In function ‘kasan_unpoison_task_stack_below’: mm/kasan/kasan.c:82:34: warning: passing argument 2 of ‘__kasan_unpoison_stack’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers] __kasan_unpoison_stack(current, watermark); ^~~~~~~~~ mm/kasan/kasan.c:65:13: note: expected ‘void *’ but argument is of type ‘const void *’ static void __kasan_unpoison_stack(struct task_struct *task, void *sp) ^~~~~~~~~~~~~~~~~~~~~~ mm/kasan/kasan.c: In function ‘kasan_unpoison_stack_above_sp_to’: mm/kasan/kasan.c:92:27: error: called object ‘current_stack_pointer’ is not a function or function pointer const void *sp = (void *)current_stack_pointer(); ^~~~~~~~~~~~~~~~~~~~~ In file included from ./include/linux/thread_info.h:54:0, from ./include/asm-generic/preempt.h:4, from ./arch/arm64/include/generated/asm/preempt.h:1, from ./include/linux/preempt.h:59, from ./include/linux/interrupt.h:8, from mm/kasan/kasan.c:20: ./arch/arm64/include/asm/thread_info.h:69:24: note: declared here register unsigned long current_stack_pointer asm ("sp");
Will
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