Messages in this thread | | | Date | Mon, 11 Oct 2021 14:03:26 -0700 | From | Kees Cook <> | Subject | Re: [PATCH] x86/unwind/orc: Handle kretprobes_trampoline |
| |
On Thu, Sep 02, 2021 at 07:13:26PM -0700, Kees Cook wrote: > From: Marios Pomonis <pomonis@google.com> > > Fix a bug in the ORC unwinder when kretprobes has replaced a return > address with the address of `kretprobes_trampoline'. ORC mistakenly > assumes that the address in the stack is a return address and decrements > it by 1 in order to find the proper depth of the next frame. > > This issue was discovered while testing the FG-KASLR series[0][1] and > running the live patching test[2] that was originally failing[3]. > > [0] https://lore.kernel.org/kernel-hardening/20200923173905.11219-1-kristen@linux.intel.com/ > [1] https://github.com/KSPP/linux/issues/132 > [2] https://github.com/lpechacek/qa_test_klp > [3] https://lore.kernel.org/lkml/alpine.LSU.2.21.2009251450260.13615@pobox.suse.cz/ > > Fixes: ee9f8fce9964 ("x86/unwind: Add the ORC unwinder") > Signed-off-by: Marios Pomonis <pomonis@google.com> > Cc: Josh Poimboeuf <jpoimboe@redhat.com> > Cc: Alexander Lobakin <alexandr.lobakin@intel.com> > Cc: Kristen C Accardi <kristen.c.accardi@intel.com> > Cc: Sami Tolvanen <samitolvanen@google.com> > Signed-off-by: Kees Cook <keescook@chromium.org>
Ping again; Josh can you take this please?
-Kees
> --- > arch/x86/kernel/unwind_orc.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c > index a1202536fc57..8c5038b3b707 100644 > --- a/arch/x86/kernel/unwind_orc.c > +++ b/arch/x86/kernel/unwind_orc.c > @@ -7,6 +7,7 @@ > #include <asm/unwind.h> > #include <asm/orc_types.h> > #include <asm/orc_lookup.h> > +#include <asm/kprobes.h> > > #define orc_warn(fmt, ...) \ > printk_deferred_once(KERN_WARNING "WARNING: " fmt, ##__VA_ARGS__) > @@ -414,6 +415,15 @@ static bool get_reg(struct unwind_state *state, unsigned int reg_off, > return false; > } > > +static bool is_kretprobe_trampoline(unsigned long ip) > +{ > +#ifdef CONFIG_KRETPROBES > + if (ip == (unsigned long)&kretprobe_trampoline) > + return true; > +#endif > + return false; > +} > + > bool unwind_next_frame(struct unwind_state *state) > { > unsigned long ip_p, sp, tmp, orig_ip = state->ip, prev_sp = state->sp; > @@ -540,7 +550,7 @@ bool unwind_next_frame(struct unwind_state *state) > state->sp = sp; > state->regs = NULL; > state->prev_regs = NULL; > - state->signal = false; > + state->signal = is_kretprobe_trampoline(state->ip); > break; > > case UNWIND_HINT_TYPE_REGS: > -- > 2.30.2 >
-- Kees Cook
| |