[PATCH bpf 1/4] ARM: unwind: Initialize the lr_addr field of unwind_ctrl_block

Masami Hiramatsu
2022-04-06T00:21:40Z

Since the unwind_ctrl_block::lr_addr is finally passed to
stackframe::lr_addr, that value will be exposed unconditionally.
Thus it should be initialized.

Without this fix, when unwind_frame() doesn't update the
unwind_ctrl_block::lr_addr (e.g. 'lr' register is not saved in the
target function), stackframe::lr_addr will contain a wrong value.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
arch/arm/kernel/unwind.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
index a37ea6c772cd..93e767682cf4 100644
--- a/arch/arm/kernel/unwind.c
+++ b/arch/arm/kernel/unwind.c
@@ -404,6 +404,7 @@ int unwind_frame(struct stackframe *frame)
ctrl.vrs[SP] = frame->sp;
ctrl.vrs[LR] = frame->lr;
ctrl.vrs[PC] = 0;
+ ctrl.lr_addr = 0;

if (idx->insn == 1)
/* can't unwind */