linux-kernel - [PATCH 5.15 218/244] RISC-V: Add fast call path of crash

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

Message-Id: <20220823080106.799832477@linuxfoundation.org>
Date:   Tue, 23 Aug 2022 10:26:17 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Guo Ren <guoren@...nel.org>,
        Xianting Tian <xianting.tian@...ux.alibaba.com>,
        Palmer Dabbelt <palmer@...osinc.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 218/244] RISC-V: Add fast call path of crash_kexec()

From: Xianting Tian <xianting.tian@...ux.alibaba.com>

[ Upstream commit 3f1901110a89b0e2e13adb2ac8d1a7102879ea98 ]

Currently, almost all archs (x86, arm64, mips...) support fast call
of crash_kexec() when "regs && kexec_should_crash()" is true. But
RISC-V not, it can only enter crash system via panic(). However panic()
doesn't pass the regs of the real accident scene to crash_kexec(),
it caused we can't get accurate backtrace via gdb,
	$ riscv64-linux-gnu-gdb vmlinux vmcore
	Reading symbols from vmlinux...
	[New LWP 95]
	#0  console_unlock () at kernel/printk/printk.c:2557
	2557                    if (do_cond_resched)
	(gdb) bt
	#0  console_unlock () at kernel/printk/printk.c:2557
	#1  0x0000000000000000 in ?? ()

With the patch we can get the accurate backtrace,
	$ riscv64-linux-gnu-gdb vmlinux vmcore
	Reading symbols from vmlinux...
	[New LWP 95]
	#0  0xffffffe00063a4e0 in test_thread (data=<optimized out>) at drivers/test_crash.c:81
	81             *(int *)p = 0xdead;
	(gdb)
	(gdb) bt
	#0  0xffffffe00064d5c0 in test_thread (data=<optimized out>) at drivers/test_crash.c:81
	#1  0x0000000000000000 in ?? ()

Test code to produce NULL address dereference in test_crash.c,
	void *p = NULL;
	*(int *)p = 0xdead;

Reviewed-by: Guo Ren <guoren@...nel.org>
Tested-by: Xianting Tian <xianting.tian@...ux.alibaba.com>
Signed-off-by: Xianting Tian <xianting.tian@...ux.alibaba.com>
Link: https://lore.kernel.org/r/20220606082308.2883458-1-xianting.tian@linux.alibaba.com
Signed-off-by: Palmer Dabbelt <palmer@...osinc.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/riscv/kernel/traps.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 0daaa3e4630d..b938ffe129d6 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -16,6 +16,7 @@
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/irq.h>
+#include <linux/kexec.h>
 
 #include <asm/asm-prototypes.h>
 #include <asm/bug.h>
@@ -44,6 +45,9 @@ void die(struct pt_regs *regs, const char *str)
 
 	ret = notify_die(DIE_OOPS, str, regs, 0, regs->cause, SIGSEGV);
 
+	if (regs && kexec_should_crash(current))
+		crash_kexec(regs);
+
 	bust_spinlocks(0);
 	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 	spin_unlock_irq(&die_lock);
-- 
2.35.1