diff options
Diffstat (limited to 'arch/arm64/kernel/stacktrace.c')
| -rw-r--r-- | arch/arm64/kernel/stacktrace.c | 40 |
1 files changed, 39 insertions, 1 deletions
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index 017972c2de90..2b160ae594eb 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -29,9 +29,18 @@ * ldp x29, x30, [sp] * add sp, sp, #0x10 */ + +/* + * Unwind from one frame record (A) to the next frame record (B). + * + * We terminate early if the location of B indicates a malformed chain of frame + * records (e.g. a cycle), determined based on the location and fp value of A + * and the location (but not the fp value) of B. + */ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) { unsigned long fp = frame->fp; + struct stack_info info; if (fp & 0xf) return -EINVAL; @@ -39,11 +48,40 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) if (!tsk) tsk = current; - if (!on_accessible_stack(tsk, fp, NULL)) + if (!on_accessible_stack(tsk, fp, &info)) return -EINVAL; + if (test_bit(info.type, frame->stacks_done)) + return -EINVAL; + + /* + * As stacks grow downward, any valid record on the same stack must be + * at a strictly higher address than the prior record. + * + * Stacks can nest in several valid orders, e.g. + * + * TASK -> IRQ -> OVERFLOW -> SDEI_NORMAL + * TASK -> SDEI_NORMAL -> SDEI_CRITICAL -> OVERFLOW + * + * ... but the nesting itself is strict. Once we transition from one + * stack to another, it's never valid to unwind back to that first + * stack. + */ + if (info.type == frame->prev_type) { + if (fp <= frame->prev_fp) + return -EINVAL; + } else { + set_bit(frame->prev_type, frame->stacks_done); + } + + /* + * Record this frame record's values and location. The prev_fp and + * prev_type are only meaningful to the next unwind_frame() invocation. + */ frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp)); frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8)); + frame->prev_fp = fp; + frame->prev_type = info.type; #ifdef CONFIG_FUNCTION_GRAPH_TRACER if (tsk->ret_stack && |