linux-kernel - [PATCH v2] ARM: mm: Facilitate debugging CONFIG_KUSER

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

Message-Id: <20181025190110.7564-1-f.fainelli@gmail.com>
Date:   Thu, 25 Oct 2018 12:01:08 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     andrew@...n.ch, ebiederm@...ssion.com,
        Florian Fainelli <f.fainelli@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Souptick Joarder <jrdr.linux@...il.com>,
        Tony Lindgren <tony@...mide.com>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v2] ARM: mm: Facilitate debugging CONFIG_KUSER_HELPERS disabled

Some software such as perf makes unconditional use of the special
[vectors] page which is only provided when CONFIG_KUSER_HELPERS is
enabled in the kernel.

Facilitate the debugging of such situations by printing a debug message
to the kernel log showing the task name and the faulting address.

Suggested-by: Russell King <rmk+kernel@...linux.org.uk>
Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
---
 arch/arm/mm/fault.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index f4ea4c62c613..58f69fa07df9 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -173,6 +173,12 @@ __do_user_fault(struct task_struct *tsk, unsigned long addr,
 		show_regs(regs);
 	}
 #endif
+#ifndef CONFIG_KUSER_HELPERS
+	if ((sig == SIGSEGV) && ((addr & PAGE_MASK) == 0xffff0000))
+		printk_ratelimited(KERN_DEBUG
+				   "%s: CONFIG_KUSER_HELPERS disabled at 0x%08lx\n",
+				   tsk->comm, addr);
+#endif
 
 	tsk->thread.address = addr;
 	tsk->thread.error_code = fsr;
-- 
2.17.1