linux-kernel - [PATCH v2] riscv: stacktrace: fix stackframe without ra on the top

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20201128062242.825448-1-chenhuang5@huawei.com>
Date:   Sat, 28 Nov 2020 06:22:42 +0000
From:   Chen Huang <chenhuang5@...wei.com>
To:     <wangkefeng.wang@...wei.com>
CC:     <akpm@...ux-foundation.org>, <aou@...s.berkeley.edu>,
        <chenhuang5@...wei.com>, <linux-kernel@...r.kernel.org>,
        <linux-riscv@...ts.infradead.org>, <palmer@...belt.com>,
        <paul.walmsley@...ive.com>
Subject: [PATCH v2] riscv: stacktrace: fix stackframe without ra on the top

When a function doesn't have a callee, then it will not push ra
into the stack, such as lkdtm_BUG() function:

addi	sp,sp,-16
sd		s0,8(sp)
addi	s0,sp,16
ebreak

The struct stackframe use {fp,ra} to get information from
stack, if walk_stackframe() with pr_regs, we will obtain
wrong value and bad stacktrace,

[<ffffffe00066c56c>] lkdtm_BUG+0x6/0x8
---[ end trace 18da3fbdf08e25d5 ]---

Correct the next fp and pc, after that, full stacktrace
shown as expects,

[<ffffffe00066c56c>] lkdtm_BUG+0x6/0x8
[<ffffffe0008b24a4>] lkdtm_do_action+0x14/0x1c
[<ffffffe00066c372>] direct_entry+0xc0/0x10a
[<ffffffe000439f86>] full_proxy_write+0x42/0x6a
[<ffffffe000309626>] vfs_write+0x7e/0x214
[<ffffffe00030992a>] ksys_write+0x98/0xc0
[<ffffffe000309960>] sys_write+0xe/0x16
[<ffffffe0002014bc>] ret_from_syscall+0x0/0x2
---[ end trace 61917f3d9a9fadcd ]---

Signed-off-by: Chen Huang <chenhuang5@...wei.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
---
 arch/riscv/kernel/stacktrace.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
index 595342910c3f..3842fac26e85 100644
--- a/arch/riscv/kernel/stacktrace.c
+++ b/arch/riscv/kernel/stacktrace.c
@@ -57,9 +57,14 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
 		/* Unwind stack frame */
 		frame = (struct stackframe *)fp - 1;
 		sp = fp;
-		fp = frame->fp;
-		pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
-					   (unsigned long *)(fp - 8));
+		if (regs && (pc == regs->epc) && (frame->fp & 0x7)) {
+			fp = frame->ra;
+			pc = regs->ra;
+		} else {
+			fp = frame->fp;
+			pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
+						(unsigned long *)(fp - 8));
+		}
 	}
 }
 
-- 
2.17.1