Commit 3667dafd authored Apr 06, 2017 by Joerg Roedel Committed by Greg Kroah-Hartman Jul 05, 2017

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



commit 5ed386ec09a5d75bcf073967e55e895c2607a5c3 upstream.

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@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: fe3d197f ('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@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent b287ade8

arch/x86/mm/mpx.c

+1 −9

Original line number	Diff line number	Diff line
		@@ -525,15 +525,7 @@ 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();
		}

		/*