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From: Jiashuo Liang <liangjs@pku.edu.cn>
To: Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>
Cc: linux-kernel@vger.kernel.org, Jiashuo Liang <liangjs@pku.edu.cn>
Subject: [PATCH] signal/x86: Don't send SIGSEGV twice on SEGV_PKUERR
Date: Tue,  1 Jun 2021 16:52:03 +0800
Message-ID: <20210601085203.40214-1-liangjs@pku.edu.cn> (raw)

Before this patch, the __bad_area_nosemaphore function calls both
force_sig_pkuerr and force_sig_fault when handling SEGV_PKUERR. This does
not cause problems because the second signal is filtered by the
legacy_queue check in __send_signal. But it causes the kernel to do
unnecessary work.

This patch should fix it.

Fixes: 9db812dbb29d ("signal/x86: Call force_sig_pkuerr from __bad_area_nosemaphore")
Suggested-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Jiashuo Liang <liangjs@pku.edu.cn>
---
 arch/x86/mm/fault.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 1c548ad00752..6bda7f67d737 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -836,8 +836,8 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
 
 	if (si_code == SEGV_PKUERR)
 		force_sig_pkuerr((void __user *)address, pkey);
-
-	force_sig_fault(SIGSEGV, si_code, (void __user *)address);
+	else
+		force_sig_fault(SIGSEGV, si_code, (void __user *)address);
 
 	local_irq_disable();
 }
-- 
2.31.1


             reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-01  8:52 Jiashuo Liang [this message]
2021-06-02 18:42 ` Eric W. Biederman
2021-06-02 19:02   ` Borislav Petkov
2021-06-03 18:37 ` Borislav Petkov
2021-06-03 21:31   ` Eric W. Biederman
2021-06-04 13:06     ` Borislav Petkov
2021-06-04 14:33       ` Eric W. Biederman
2021-06-04 14:54         ` Borislav Petkov
2021-06-04 13:26 ` [tip: x86/urgent] x86/fault: " tip-bot2 for Jiashuo Liang

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