From: madvenka@linux.microsoft.com To: broonie@kernel.org, jpoimboe@redhat.com, mark.rutland@arm.com, jthierry@redhat.com, catalin.marinas@arm.com, will@kernel.org, jmorris@namei.org, pasha.tatashin@soleen.com, linux-arm-kernel@lists.infradead.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, madvenka@linux.microsoft.com Subject: [RFC PATCH v3 1/4] arm64: Introduce stack trace reliability checks in the unwinder Date: Mon, 3 May 2021 12:36:12 -0500 [thread overview] Message-ID: <20210503173615.21576-2-madvenka@linux.microsoft.com> (raw) In-Reply-To: <20210503173615.21576-1-madvenka@linux.microsoft.com> From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com> The unwinder should check for the presence of various features and conditions that can render the stack trace unreliable and mark the the stack trace as unreliable for the benefit of the caller. Introduce the first reliability check - If a return PC encountered in a stack trace is not a valid kernel text address, the stack trace is considered unreliable. It could be some generated code. Mark the stack trace unreliable. Other reliability checks will be added in the future. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> --- arch/arm64/include/asm/stacktrace.h | 4 ++++ arch/arm64/kernel/stacktrace.c | 19 ++++++++++++++++--- 2 files changed, 20 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h index eb29b1fe8255..f1eab6b029f7 100644 --- a/arch/arm64/include/asm/stacktrace.h +++ b/arch/arm64/include/asm/stacktrace.h @@ -49,6 +49,8 @@ struct stack_info { * * @graph: When FUNCTION_GRAPH_TRACER is selected, holds the index of a * replacement lr value in the ftrace graph stack. + * + * @reliable: Is this stack frame reliable? */ struct stackframe { unsigned long fp; @@ -59,6 +61,7 @@ struct stackframe { #ifdef CONFIG_FUNCTION_GRAPH_TRACER int graph; #endif + bool reliable; }; extern int unwind_frame(struct task_struct *tsk, struct stackframe *frame); @@ -169,6 +172,7 @@ static inline void start_backtrace(struct stackframe *frame, bitmap_zero(frame->stacks_done, __NR_STACK_TYPES); frame->prev_fp = 0; frame->prev_type = STACK_TYPE_UNKNOWN; + frame->reliable = true; } #endif /* __ASM_STACKTRACE_H */ diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index d55bdfb7789c..c21a1bca28f3 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -44,6 +44,8 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) unsigned long fp = frame->fp; struct stack_info info; + frame->reliable = true; + /* Terminal record; nothing to unwind */ if (!fp) return -ENOENT; @@ -86,12 +88,24 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) */ frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp)); frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8)); + frame->pc = ptrauth_strip_insn_pac(frame->pc); frame->prev_fp = fp; frame->prev_type = info.type; + /* + * First, make sure that the return address is a proper kernel text + * address. A NULL or invalid return address probably means there's + * some generated code which __kernel_text_address() doesn't know + * about. Mark the stack trace as not reliable. + */ + if (!__kernel_text_address(frame->pc)) { + frame->reliable = false; + return 0; + } + #ifdef CONFIG_FUNCTION_GRAPH_TRACER if (tsk->ret_stack && - (ptrauth_strip_insn_pac(frame->pc) == (unsigned long)return_to_handler)) { + frame->pc == (unsigned long)return_to_handler) { struct ftrace_ret_stack *ret_stack; /* * This is a case where function graph tracer has @@ -103,11 +117,10 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) if (WARN_ON_ONCE(!ret_stack)) return -EINVAL; frame->pc = ret_stack->ret; + frame->pc = ptrauth_strip_insn_pac(frame->pc); } #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ - frame->pc = ptrauth_strip_insn_pac(frame->pc); - return 0; } NOKPROBE_SYMBOL(unwind_frame); -- 2.25.1
WARNING: multiple messages have this Message-ID (diff)
From: madvenka@linux.microsoft.com To: broonie@kernel.org, jpoimboe@redhat.com, mark.rutland@arm.com, jthierry@redhat.com, catalin.marinas@arm.com, will@kernel.org, jmorris@namei.org, pasha.tatashin@soleen.com, linux-arm-kernel@lists.infradead.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, madvenka@linux.microsoft.com Subject: [RFC PATCH v3 1/4] arm64: Introduce stack trace reliability checks in the unwinder Date: Mon, 3 May 2021 12:36:12 -0500 [thread overview] Message-ID: <20210503173615.21576-2-madvenka@linux.microsoft.com> (raw) In-Reply-To: <20210503173615.21576-1-madvenka@linux.microsoft.com> From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com> The unwinder should check for the presence of various features and conditions that can render the stack trace unreliable and mark the the stack trace as unreliable for the benefit of the caller. Introduce the first reliability check - If a return PC encountered in a stack trace is not a valid kernel text address, the stack trace is considered unreliable. It could be some generated code. Mark the stack trace unreliable. Other reliability checks will be added in the future. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> --- arch/arm64/include/asm/stacktrace.h | 4 ++++ arch/arm64/kernel/stacktrace.c | 19 ++++++++++++++++--- 2 files changed, 20 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h index eb29b1fe8255..f1eab6b029f7 100644 --- a/arch/arm64/include/asm/stacktrace.h +++ b/arch/arm64/include/asm/stacktrace.h @@ -49,6 +49,8 @@ struct stack_info { * * @graph: When FUNCTION_GRAPH_TRACER is selected, holds the index of a * replacement lr value in the ftrace graph stack. + * + * @reliable: Is this stack frame reliable? */ struct stackframe { unsigned long fp; @@ -59,6 +61,7 @@ struct stackframe { #ifdef CONFIG_FUNCTION_GRAPH_TRACER int graph; #endif + bool reliable; }; extern int unwind_frame(struct task_struct *tsk, struct stackframe *frame); @@ -169,6 +172,7 @@ static inline void start_backtrace(struct stackframe *frame, bitmap_zero(frame->stacks_done, __NR_STACK_TYPES); frame->prev_fp = 0; frame->prev_type = STACK_TYPE_UNKNOWN; + frame->reliable = true; } #endif /* __ASM_STACKTRACE_H */ diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index d55bdfb7789c..c21a1bca28f3 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -44,6 +44,8 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) unsigned long fp = frame->fp; struct stack_info info; + frame->reliable = true; + /* Terminal record; nothing to unwind */ if (!fp) return -ENOENT; @@ -86,12 +88,24 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) */ frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp)); frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8)); + frame->pc = ptrauth_strip_insn_pac(frame->pc); frame->prev_fp = fp; frame->prev_type = info.type; + /* + * First, make sure that the return address is a proper kernel text + * address. A NULL or invalid return address probably means there's + * some generated code which __kernel_text_address() doesn't know + * about. Mark the stack trace as not reliable. + */ + if (!__kernel_text_address(frame->pc)) { + frame->reliable = false; + return 0; + } + #ifdef CONFIG_FUNCTION_GRAPH_TRACER if (tsk->ret_stack && - (ptrauth_strip_insn_pac(frame->pc) == (unsigned long)return_to_handler)) { + frame->pc == (unsigned long)return_to_handler) { struct ftrace_ret_stack *ret_stack; /* * This is a case where function graph tracer has @@ -103,11 +117,10 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) if (WARN_ON_ONCE(!ret_stack)) return -EINVAL; frame->pc = ret_stack->ret; + frame->pc = ptrauth_strip_insn_pac(frame->pc); } #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ - frame->pc = ptrauth_strip_insn_pac(frame->pc); - return 0; } NOKPROBE_SYMBOL(unwind_frame); -- 2.25.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-05-03 17:36 UTC|newest] Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <65cf4dfbc439b010b50a0c46ec500432acde86d6> 2021-05-03 17:36 ` [RFC PATCH v3 0/4] arm64: Stack trace reliability checks in the unwinder madvenka 2021-05-03 17:36 ` madvenka 2021-05-03 17:36 ` madvenka [this message] 2021-05-03 17:36 ` [RFC PATCH v3 1/4] arm64: Introduce stack " madvenka 2021-05-04 15:50 ` Mark Brown 2021-05-04 15:50 ` Mark Brown 2021-05-04 19:14 ` Madhavan T. Venkataraman 2021-05-04 19:14 ` Madhavan T. Venkataraman 2021-05-04 21:52 ` Josh Poimboeuf 2021-05-04 21:52 ` Josh Poimboeuf 2021-05-04 23:13 ` Madhavan T. Venkataraman 2021-05-04 23:13 ` Madhavan T. Venkataraman 2021-05-05 0:07 ` Josh Poimboeuf 2021-05-05 0:07 ` Josh Poimboeuf 2021-05-05 0:21 ` Madhavan T. Venkataraman 2021-05-05 0:21 ` Madhavan T. Venkataraman 2021-05-03 17:36 ` [RFC PATCH v3 2/4] arm64: Check the return PC against unreliable code sections madvenka 2021-05-03 17:36 ` madvenka 2021-05-04 16:05 ` Mark Brown 2021-05-04 16:05 ` Mark Brown 2021-05-04 19:03 ` Madhavan T. Venkataraman 2021-05-04 19:03 ` Madhavan T. Venkataraman 2021-05-04 19:32 ` Madhavan T. Venkataraman 2021-05-04 19:32 ` Madhavan T. Venkataraman 2021-05-05 16:46 ` Mark Brown 2021-05-05 16:46 ` Mark Brown 2021-05-05 18:48 ` Madhavan T. Venkataraman 2021-05-05 18:48 ` Madhavan T. Venkataraman 2021-05-05 18:50 ` Madhavan T. Venkataraman 2021-05-05 18:50 ` Madhavan T. Venkataraman 2021-05-06 13:45 ` Mark Brown 2021-05-06 13:45 ` Mark Brown 2021-05-06 15:21 ` Madhavan T. Venkataraman 2021-05-06 15:21 ` Madhavan T. Venkataraman 2021-05-05 16:34 ` Mark Brown 2021-05-05 16:34 ` Mark Brown 2021-05-05 17:51 ` Madhavan T. Venkataraman 2021-05-05 17:51 ` Madhavan T. Venkataraman 2021-05-05 19:30 ` Ard Biesheuvel 2021-05-05 19:30 ` Ard Biesheuvel 2021-05-05 20:00 ` Madhavan T. Venkataraman 2021-05-05 20:00 ` Madhavan T. Venkataraman 2021-05-03 17:36 ` [RFC PATCH v3 3/4] arm64: Handle miscellaneous functions in .text and .init.text madvenka 2021-05-03 17:36 ` madvenka 2021-05-06 14:12 ` Mark Brown 2021-05-06 14:12 ` Mark Brown 2021-05-06 15:30 ` Madhavan T. Venkataraman 2021-05-06 15:30 ` Madhavan T. Venkataraman 2021-05-06 15:32 ` Madhavan T. Venkataraman 2021-05-06 15:32 ` Madhavan T. Venkataraman 2021-05-06 15:44 ` Mark Brown 2021-05-06 15:44 ` Mark Brown 2021-05-06 15:56 ` Madhavan T. Venkataraman 2021-05-06 15:56 ` Madhavan T. Venkataraman 2021-05-06 15:37 ` Mark Brown 2021-05-06 15:37 ` Mark Brown 2021-05-06 15:57 ` Madhavan T. Venkataraman 2021-05-06 15:57 ` Madhavan T. Venkataraman 2021-05-03 17:36 ` [RFC PATCH v3 4/4] arm64: Handle funtion graph tracer better in the unwinder madvenka 2021-05-03 17:36 ` madvenka 2021-05-06 14:43 ` Mark Brown 2021-05-06 14:43 ` Mark Brown 2021-05-06 15:20 ` Madhavan T. Venkataraman 2021-05-06 15:20 ` Madhavan T. Venkataraman
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