linux-kernel - [tip:x86/mm] x86/mpx: Correctly report do_mpx_bt

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Message-ID: <tip-5ed386ec09a5d75bcf073967e55e895c2607a5c3@git.kernel.org>
Date:   Wed, 12 Apr 2017 00:30:58 -0700
From:   tip-bot for Joerg Roedel <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     jpoimboe@...hat.com, dvlasenk@...hat.com, peterz@...radead.org,
        jroedel@...e.de, tglx@...utronix.de, brgerst@...il.com,
        dave.hansen@...ux.intel.com, linux-kernel@...r.kernel.org,
        hpa@...or.com, luto@...nel.org, torvalds@...ux-foundation.org,
        bp@...en8.de, mingo@...nel.org
Subject: [tip:x86/mm] x86/mpx: Correctly report do_mpx_bt_fault() failures
 to user-space

Commit-ID:  5ed386ec09a5d75bcf073967e55e895c2607a5c3
Gitweb:     http://git.kernel.org/tip/5ed386ec09a5d75bcf073967e55e895c2607a5c3
Author:     Joerg Roedel <jroedel@...e.de>
AuthorDate: Thu, 6 Apr 2017 16:19:22 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 12 Apr 2017 08:40:58 +0200

x86/mpx: Correctly report do_mpx_bt_fault() failures to user-space

When this function fails it just sends a SIGSEGV signal to
user-space using force_sig(). This signal is missing
essential information about the cause, e.g. the trap_nr or
an error code.

Fix this by propagating the error to the only caller of
mpx_handle_bd_fault(), do_bounds(), which sends the correct
SIGSEGV signal to the process.

Signed-off-by: Joerg Roedel <jroedel@...e.de>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Fixes: fe3d197f84319 ('x86, mpx: On-demand kernel allocation of bounds tables')
Link: http://lkml.kernel.org/r/1491488362-27198-1-git-send-email-joro@8bytes.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/mm/mpx.c | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index cd44ae7..1c34b76 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -526,15 +526,7 @@ int mpx_handle_bd_fault(void)
 	if (!kernel_managing_mpx_tables(current->mm))
 		return -EINVAL;
 
-	if (do_mpx_bt_fault()) {
-		force_sig(SIGSEGV, current);
-		/*
-		 * The force_sig() is essentially "handling" this
-		 * exception, so we do not pass up the error
-		 * from do_mpx_bt_fault().
-		 */
-	}
-	return 0;
+	return do_mpx_bt_fault();
 }
 
 /*