4.9-stable review patch. If anyone has any objections, please let me know.
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From: Eric W. Biederman ebiederm@xmission.com
commit beacd6f7ed5e2915959442245b3b2480c2e37490 upstream.
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.
This error was by inspection, and BUS_MCEERR_AR appears to be a real candidate for confusion. So pass in si_signo and check for SIG_SEGV to verify that it is actually a SEGV_PKUERR
Fixes: 019132ff3daf ("x86/mm/pkeys: Fill in pkey field in siginfo") Signed-off-by: "Eric W. Biederman" ebiederm@xmission.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: linux-arch@vger.kernel.org Cc: Dave Hansen dave.hansen@linux.intel.com Cc: Oleg Nesterov oleg@redhat.com Cc: Al Viro viro@zeniv.linux.org.uk Link: https://lkml.kernel.org/r/20180112203135.4669-2-ebiederm@xmission.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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 @@ -191,14 +191,15 @@ 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 @@ -237,7 +238,7 @@ 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); }