linux-kernel - [tip:x86/urgent] x86/pkeys/selftests: Fix pointer math

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Date:   Mon, 14 May 2018 05:45:20 -0700
From:   tip-bot for Dave Hansen <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     linuxram@...ibm.com, mpe@...erman.id.au, akpm@...ux-foundation.org,
        torvalds@...ux-foundation.org, peterz@...radead.org,
        mingo@...nel.org, hpa@...or.com, dave.hansen@...ux.intel.com,
        dave.hansen@...el.com, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, shuah@...nel.org
Subject: [tip:x86/urgent] x86/pkeys/selftests: Fix pointer math

Commit-ID:  3d64f4ed15c3c53dba4c514bf59c334464dee373
Gitweb:     https://git.kernel.org/tip/3d64f4ed15c3c53dba4c514bf59c334464dee373
Author:     Dave Hansen <dave.hansen@...ux.intel.com>
AuthorDate: Wed, 9 May 2018 10:13:52 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 14 May 2018 11:14:45 +0200

x86/pkeys/selftests: Fix pointer math

We dump out the entire area of the siginfo where the si_pkey_ptr is
supposed to be.  But, we do some math on the poitner, which is a u32.
We intended to do byte math, not u32 math on the pointer.

Cast it over to a u8* so it works.

Also, move this block of code to below th si_code check.  It doesn't
hurt anything, but the si_pkey field is gibberish for other signal
types.

Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Michael Ellermen <mpe@...erman.id.au>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ram Pai <linuxram@...ibm.com>
Cc: Shuah Khan <shuah@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-mm@...ck.org
Link: http://lkml.kernel.org/r/20180509171352.9BE09819@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 tools/testing/selftests/x86/protection_keys.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/x86/protection_keys.c b/tools/testing/selftests/x86/protection_keys.c
index 55a4e349a45e..ee8176358d12 100644
--- a/tools/testing/selftests/x86/protection_keys.c
+++ b/tools/testing/selftests/x86/protection_keys.c
@@ -303,13 +303,6 @@ void signal_handler(int signum, siginfo_t *si, void *vucontext)
 		dump_mem(pkru_ptr - 128, 256);
 	pkey_assert(*pkru_ptr);
 
-	si_pkey_ptr = (u32 *)(((u8 *)si) + si_pkey_offset);
-	dprintf1("si_pkey_ptr: %p\n", si_pkey_ptr);
-	dump_mem(si_pkey_ptr - 8, 24);
-	siginfo_pkey = *si_pkey_ptr;
-	pkey_assert(siginfo_pkey < NR_PKEYS);
-	last_si_pkey = siginfo_pkey;
-
 	if ((si->si_code == SEGV_MAPERR) ||
 	    (si->si_code == SEGV_ACCERR) ||
 	    (si->si_code == SEGV_BNDERR)) {
@@ -317,6 +310,13 @@ void signal_handler(int signum, siginfo_t *si, void *vucontext)
 		exit(4);
 	}
 
+	si_pkey_ptr = (u32 *)(((u8 *)si) + si_pkey_offset);
+	dprintf1("si_pkey_ptr: %p\n", si_pkey_ptr);
+	dump_mem((u8 *)si_pkey_ptr - 8, 24);
+	siginfo_pkey = *si_pkey_ptr;
+	pkey_assert(siginfo_pkey < NR_PKEYS);
+	last_si_pkey = siginfo_pkey;
+
 	dprintf1("signal pkru from xsave: %08x\n", *pkru_ptr);
 	/* need __rdpkru() version so we do not do shadow_pkru checking */
 	dprintf1("signal pkru from  pkru: %08x\n", __rdpkru());