@@ -297,7 +297,7 @@ EXPORT_SYMBOL(dump_fpu);
unsigned long get_wchan(struct task_struct *p)
{
struct stackframe frame;
- unsigned long stack_page;
+ unsigned long stack_page, ret = 0;
int count = 0;
if (!p || p == current || p->state == TASK_RUNNING)
return 0;
@@ -306,16 +306,25 @@ unsigned long get_wchan(struct task_struct *p)
frame.sp = thread_saved_sp(p);
frame.lr = 0; /* recovered from the stack */
frame.pc = thread_saved_pc(p);
- stack_page = (unsigned long)task_stack_page(p);
+
+ stack_page = (unsigned long)try_get_task_stack(p);
+ if (!stack_page)
+ return 0;
+
do {
if (frame.sp < stack_page ||
frame.sp >= stack_page + THREAD_SIZE ||
unwind_frame(&frame) < 0)
- return 0;
- if (!in_sched_functions(frame.pc))
- return frame.pc;
+ goto out;
+ if (!in_sched_functions(frame.pc)) {
+ ret = frame.pc;
+ goto out;
+ }
} while (count ++ < 16);
- return 0;
+
+out:
+ put_task_stack(p);
+ return ret;
}
unsigned long arch_randomize_brk(struct mm_struct *mm)
@@ -1,6 +1,7 @@
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
+#include <linux/sched/task_stack.h>
#include <linux/stacktrace.h>
#include <asm/sections.h>
@@ -105,6 +106,9 @@ static noinline void __save_stack_trace(struct task_struct *tsk,
struct stack_trace_data data;
struct stackframe frame;
+ if (!try_get_task_stack(tsk))
+ return;
+
data.trace = trace;
data.skip = trace->skip;
data.no_sched_functions = nosched;
@@ -118,6 +122,7 @@ static noinline void __save_stack_trace(struct task_struct *tsk,
*/
if (trace->nr_entries < trace->max_entries)
trace->entries[trace->nr_entries++] = ULONG_MAX;
+ put_task_stack(tsk);
return;
#else
frame.fp = thread_saved_fp(tsk);
@@ -137,6 +142,8 @@ static noinline void __save_stack_trace(struct task_struct *tsk,
walk_stackframe(&frame, save_trace, &data);
if (trace->nr_entries < trace->max_entries)
trace->entries[trace->nr_entries++] = ULONG_MAX;
+
+ put_task_stack(tsk);
}
void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
@@ -216,6 +216,9 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
if (!tsk)
tsk = current;
+ if (!try_get_task_stack(tsk))
+ return;
+
if (regs) {
fp = frame_pointer(regs);
mode = processor_mode(regs);
@@ -239,6 +242,8 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
if (ok)
c_backtrace(fp, mode);
+
+ put_task_stack(tsk);
}
#endif
When CONFIG_THREAD_INFO_IN_TASK is enabled, thread stacks may be freed before a stack is destroyed. This patch adds in recounting to ensure freed stacks are not used. If CONFIG_THREAD_INFO_IN_TASK is not used, no refcounting is performed. Signed-off-by: Zubin Mithra <zsm@chromium.org> --- arch/arm/kernel/process.c | 21 +++++++++++++++------ arch/arm/kernel/stacktrace.c | 7 +++++++ arch/arm/kernel/traps.c | 5 +++++ 3 files changed, 27 insertions(+), 6 deletions(-)