From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Wed, 3 Jan 2018 19:04:34 -0600
Subject: x86/mm/pkeys: Fix fill_sig_info_pkey
Git-commit: 90bc9fb15942ad08b46cd003d8d1b51f3d43e322
Git-commit: beacd6f7ed5e2915959442245b3b2480c2e37490
Patch-mainline: v4.16-rc1
References: git-fixes, bsc#1083529

SEGV_PKUERR is a signal specific si_code which happens to have the
same numeric value as several others: BUS_MCEERR_AR, ILL_ILLTRP,
FPE_FLTOVF, TRAP_HWBKPT, CLD_TRAPPED, POLL_ERR, SEGV_THREAD_ID,
as such it is not safe to just test the si_code the signal number
must also be tested to prevent a false positive in fill_sig_info_pkey.

I found this error by inspection, and BUS_MCEERR_AR appears to
be a real candidate for confusion.  So pass in si_signo and fix it.

Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Fixes: 019132ff3daf ("x86/mm/pkeys: Fill in pkey field in siginfo")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
 arch/x86/mm/fault.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -192,14 +192,15 @@ is_prefetch(struct pt_regs *regs, unsign
  * 6. T1   : reaches here, sees vma_pkey(vma)=5, when we really
  *	     faulted on a pte with its pkey=4.
  */
-static void fill_sig_info_pkey(int si_code, siginfo_t *info, u32 *pkey)
+static void fill_sig_info_pkey(int si_signo, int si_code, siginfo_t *info,
+		u32 *pkey)
 {
 	/* This is effectively an #ifdef */
 	if (!boot_cpu_has(X86_FEATURE_OSPKE))
 		return;
 
 	/* Fault not from Protection Keys: nothing to do */
-	if (si_code != SEGV_PKUERR)
+	if ((si_code != SEGV_PKUERR) || (si_signo != SIGSEGV))
 		return;
 	/*
 	 * force_sig_info_fault() is called from a number of
@@ -238,7 +239,7 @@ force_sig_info_fault(int si_signo, int s
 		lsb = PAGE_SHIFT;
 	info.si_addr_lsb = lsb;
 
-	fill_sig_info_pkey(si_code, &info, pkey);
+	fill_sig_info_pkey(si_signo, si_code, &info, pkey);
 
 	force_sig_info(si_signo, &info, tsk);
 }