linux-kernel - [PATCH 5.4 065/408] x86/nmi: Fix nmi

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: <20201027135458.070641055@linuxfoundation.org>
Date:   Tue, 27 Oct 2020 14:50:03 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Libing Zhou <libing.zhou@...ia-sbell.com>,
        Borislav Petkov <bp@...e.de>,
        Changbin Du <changbin.du@...il.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 065/408] x86/nmi: Fix nmi_handle() duration miscalculation

From: Libing Zhou <libing.zhou@...ia-sbell.com>

[ Upstream commit f94c91f7ba3ba7de2bc8aa31be28e1abb22f849e ]

When nmi_check_duration() is checking the time an NMI handler took to
execute, the whole_msecs value used should be read from the @duration
argument, not from the ->max_duration, the latter being used to store
the current maximal duration.

 [ bp: Rewrite commit message. ]

Fixes: 248ed51048c4 ("x86/nmi: Remove irq_work from the long duration NMI handler")
Suggested-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Libing Zhou <libing.zhou@...ia-sbell.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: Changbin Du <changbin.du@...il.com>
Link: https://lkml.kernel.org/r/20200820025641.44075-1-libing.zhou@nokia-sbell.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/kernel/nmi.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 54c21d6abd5ac..5bb001c0c771a 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -106,7 +106,6 @@ fs_initcall(nmi_warning_debugfs);
 
 static void nmi_check_duration(struct nmiaction *action, u64 duration)
 {
-	u64 whole_msecs = READ_ONCE(action->max_duration);
 	int remainder_ns, decimal_msecs;
 
 	if (duration < nmi_longest_ns || duration < action->max_duration)
@@ -114,12 +113,12 @@ static void nmi_check_duration(struct nmiaction *action, u64 duration)
 
 	action->max_duration = duration;
 
-	remainder_ns = do_div(whole_msecs, (1000 * 1000));
+	remainder_ns = do_div(duration, (1000 * 1000));
 	decimal_msecs = remainder_ns / 1000;
 
 	printk_ratelimited(KERN_INFO
 		"INFO: NMI handler (%ps) took too long to run: %lld.%03d msecs\n",
-		action->handler, whole_msecs, decimal_msecs);
+		action->handler, duration, decimal_msecs);
 }
 
 static int nmi_handle(unsigned int type, struct pt_regs *regs)
-- 
2.25.1