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

From: Joerg Roedel <joro@8bytes.org>
To: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org, Dave Hansen <dave.hansen@linux.intel.com>,
	linux-kernel@vger.kernel.org, Joerg Roedel <jroedel@suse.de>
Subject: [PATCH] x86/mpx: Correctly report do_mpx_bt_fault() failures to user-space
Date: Thu,  6 Apr 2017 16:19:22 +0200	[thread overview]
Message-ID: <1491488362-27198-1-git-send-email-joro@8bytes.org> (raw)

From: Joerg Roedel <jroedel@suse.de>

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.

Fixes: fe3d197f84319 ('x86, mpx: On-demand kernel allocation of bounds tables')
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 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();
 }
 
 /*
-- 
1.9.1
