From ef1a8409348966f0b25ff97a170d6d0367710ea9 Mon Sep 17 00:00:00 2001 From: Alexander Popov Date: Tue, 13 Nov 2018 00:08:48 +0300 Subject: stackleak: Disable function tracing and kprobes for stackleak_erase() The stackleak_erase() function is called on the trampoline stack at the end of syscall. This stack is not big enough for ftrace and kprobes operations, e.g. it can be exhausted if we use kprobe_events for stackleak_erase(). So let's disable function tracing and kprobes of stackleak_erase(). Reported-by: kernel test robot Fixes: 10e9ae9fabaf ("gcc-plugins: Add STACKLEAK plugin for tracking the kernel stack") Signed-off-by: Alexander Popov Reviewed-by: Steven Rostedt (VMware) Reviewed-by: Masami Hiramatsu Signed-off-by: Kees Cook --- kernel/stackleak.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel/stackleak.c') diff --git a/kernel/stackleak.c b/kernel/stackleak.c index e42892926244..08cb57eed389 100644 --- a/kernel/stackleak.c +++ b/kernel/stackleak.c @@ -11,6 +11,7 @@ */ #include +#include #ifdef CONFIG_STACKLEAK_RUNTIME_DISABLE #include @@ -47,7 +48,7 @@ int stack_erasing_sysctl(struct ctl_table *table, int write, #define skip_erasing() false #endif /* CONFIG_STACKLEAK_RUNTIME_DISABLE */ -asmlinkage void stackleak_erase(void) +asmlinkage void notrace stackleak_erase(void) { /* It would be nice not to have 'kstack_ptr' and 'boundary' on stack */ unsigned long kstack_ptr = current->lowest_stack; @@ -101,6 +102,7 @@ asmlinkage void stackleak_erase(void) /* Reset the 'lowest_stack' value for the next syscall */ current->lowest_stack = current_top_of_stack() - THREAD_SIZE/64; } +NOKPROBE_SYMBOL(stackleak_erase); void __used stackleak_track_stack(void) { -- cgit From e9c7d656610e3fff7c96b199d418add2528aea6e Mon Sep 17 00:00:00 2001 From: Anders Roxell Date: Fri, 30 Nov 2018 16:08:59 +0100 Subject: stackleak: Mark stackleak_track_stack() as notrace Function graph tracing recurses into itself when stackleak is enabled, causing the ftrace graph selftest to run for up to 90 seconds and trigger the softlockup watchdog. Breakpoint 2, ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:200 200 mcount_get_lr_addr x0 // pointer to function's saved lr (gdb) bt \#0 ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:200 \#1 0xffffff80081d5280 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:153 \#2 0xffffff8008555484 in stackleak_track_stack () at ../kernel/stackleak.c:106 \#3 0xffffff8008421ff8 in ftrace_ops_test (ops=0xffffff8009eaa840 , ip=18446743524091297036, regs=) at ../kernel/trace/ftrace.c:1507 \#4 0xffffff8008428770 in __ftrace_ops_list_func (regs=, ignored=, parent_ip=, ip=) at ../kernel/trace/ftrace.c:6286 \#5 ftrace_ops_no_ops (ip=18446743524091297036, parent_ip=18446743524091242824) at ../kernel/trace/ftrace.c:6321 \#6 0xffffff80081d5280 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:153 \#7 0xffffff800832fd10 in irq_find_mapping (domain=0xffffffc03fc4bc80, hwirq=27) at ../kernel/irq/irqdomain.c:876 \#8 0xffffff800832294c in __handle_domain_irq (domain=0xffffffc03fc4bc80, hwirq=27, lookup=true, regs=0xffffff800814b840) at ../kernel/irq/irqdesc.c:650 \#9 0xffffff80081d52b4 in ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:205 Rework so we mark stackleak_track_stack as notrace Co-developed-by: Arnd Bergmann Signed-off-by: Arnd Bergmann Signed-off-by: Anders Roxell Acked-by: Steven Rostedt (VMware) Signed-off-by: Kees Cook --- kernel/stackleak.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/stackleak.c') diff --git a/kernel/stackleak.c b/kernel/stackleak.c index 08cb57eed389..b193a59fc05b 100644 --- a/kernel/stackleak.c +++ b/kernel/stackleak.c @@ -104,7 +104,7 @@ asmlinkage void notrace stackleak_erase(void) } NOKPROBE_SYMBOL(stackleak_erase); -void __used stackleak_track_stack(void) +void __used notrace stackleak_track_stack(void) { /* * N.B. stackleak_erase() fills the kernel stack with the poison value, -- cgit