[v1] riscv: fix out of bounds in walk_stackframe

[PATCH] riscv: fix out of bounds in walk_stackframe

Posted by Edward AD 2 years, 2 months ago

Increase the check on the frame after assigning its value. This is to prevent 
frame access from crossing boundaries.

Reported-and-tested-by: syzbot+8d2757d62d403b2d9275@syzkaller.appspotmail.com
Signed-off-by: Edward AD <twuufnxlz@gmail.com>
---
 arch/riscv/kernel/stacktrace.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
index 64a9c093aef9..53bd18672329 100644
--- a/arch/riscv/kernel/stacktrace.c
+++ b/arch/riscv/kernel/stacktrace.c
@@ -54,6 +54,8 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
 			break;
 		/* Unwind stack frame */
 		frame = (struct stackframe *)fp - 1;
+		if (!virt_addr_valid(frame))
+			break;
 		sp = fp;
 		if (regs && (regs->epc == pc) && (frame->fp & 0x7)) {
 			fp = frame->ra;
-- 
2.25.1

Re: [PATCH] riscv: fix out of bounds in walk_stackframe

Posted by Conor Dooley 2 years, 2 months ago

Hey Edward,

Where did you come up with the CC list for this patch from? Please run
get_maintainer.pl on your patches and CC the output. You've not CCed any
relevant developers on this mail :(

On Tue, Sep 26, 2023 at 06:59:50PM +0800, Edward AD wrote:
> Increase the check on the frame after assigning its value. This is to prevent 
> frame access from crossing boundaries.
> 
> Reported-and-tested-by: syzbot+8d2757d62d403b2d9275@syzkaller.appspotmail.com

Please also add a Fixes: tag & a Closes: tag with a link to the report
when you do so.

Thanks,
Conor.

> Signed-off-by: Edward AD <twuufnxlz@gmail.com>
> ---
>  arch/riscv/kernel/stacktrace.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
> index 64a9c093aef9..53bd18672329 100644
> --- a/arch/riscv/kernel/stacktrace.c
> +++ b/arch/riscv/kernel/stacktrace.c
> @@ -54,6 +54,8 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
>  			break;
>  		/* Unwind stack frame */
>  		frame = (struct stackframe *)fp - 1;
> +		if (!virt_addr_valid(frame))
> +			break;
>  		sp = fp;
>  		if (regs && (regs->epc == pc) && (frame->fp & 0x7)) {
>  			fp = frame->ra;
> -- 
> 2.25.1
>