[PATCH] riscv: fix out of bounds in walk_stackframe

[Edward AD]

Add vmalloc and kernel addresses check to prevent invalid access.

Closes: https://lore.kernel.org/all/20230926105949.1025995-2-twuufnxlz@gmail.com/
Fixes: 5d8544e2d007 ("RISC-V: Generic library routines and assembly")
Reported-and-test-by: syzbot+8d2757d62d403b2d9275 at syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/0000000000000170df0605ccf91a@google.com/T/
Signed-off-by: Edward AD <twuufnxlz at gmail.com>
---
 arch/riscv/kernel/stacktrace.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
index 64a9c093aef9..031a4a35c1d0 100644
--- a/arch/riscv/kernel/stacktrace.c
+++ b/arch/riscv/kernel/stacktrace.c
@@ -54,6 +54,9 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
 			break;
 		/* Unwind stack frame */
 		frame = (struct stackframe *)fp - 1;
+		if ((is_vmalloc_addr(frame) && !pfn_valid(page_to_pfn(vmalloc_to_page(frame)))) || 
+		     !virt_addr_valid(frame))
+			break;
 		sp = fp;
 		if (regs && (regs->epc == pc) && (frame->fp & 0x7)) {
 			fp = frame->ra;
-- 
2.25.1