Messages in this thread Patch in this message | | | From | Kees Cook <> | Subject | [PATCH] x86/unwind/orc: Handle kretprobes_trampoline | Date | Thu, 2 Sep 2021 19:13:26 -0700 |
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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> --- 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
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