linux-kernel - [PATCH 5.11 195/210] x86/traps: Correct exc_general_protection() and math

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Message-Id: <20210412084022.506578942@linuxfoundation.org>
Date:   Mon, 12 Apr 2021 10:41:40 +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, Thomas Tai <thomas.tai@...cle.com>,
        Borislav Petkov <bp@...e.de>,
        Alexandre Chartre <alexandre.chartre@...cle.com>
Subject: [PATCH 5.11 195/210] x86/traps: Correct exc_general_protection() and math_error() return paths

From: Thomas Tai <thomas.tai@...cle.com>

commit 632a1c209b8773cb0119fe3aada9f1db14fa357c upstream.

Commit

  334872a09198 ("x86/traps: Attempt to fixup exceptions in vDSO before signaling")

added return statements which bypass calling cond_local_irq_disable().

According to

  ca4c6a9858c2 ("x86/traps: Make interrupt enable/disable symmetric in C code"),

cond_local_irq_disable() is needed because the asm return code no longer
disables interrupts. Follow the existing code as an example to use "goto
exit" instead of "return" statement.

 [ bp: Massage commit message. ]

Fixes: 334872a09198 ("x86/traps: Attempt to fixup exceptions in vDSO before signaling")
Signed-off-by: Thomas Tai <thomas.tai@...cle.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@...cle.com>
Link: https://lkml.kernel.org/r/1617902914-83245-1-git-send-email-thomas.tai@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kernel/traps.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -556,7 +556,7 @@ DEFINE_IDTENTRY_ERRORCODE(exc_general_pr
 		tsk->thread.trap_nr = X86_TRAP_GP;
 
 		if (fixup_vdso_exception(regs, X86_TRAP_GP, error_code, 0))
-			return;
+			goto exit;
 
 		show_signal(tsk, SIGSEGV, "", desc, regs, error_code);
 		force_sig(SIGSEGV);
@@ -1057,7 +1057,7 @@ static void math_error(struct pt_regs *r
 		goto exit;
 
 	if (fixup_vdso_exception(regs, trapnr, 0, 0))
-		return;
+		goto exit;
 
 	force_sig_fault(SIGFPE, si_code,
 			(void __user *)uprobe_get_trap_addr(regs));