Merge tag 'v4.9.220' into 4.9-2.3.x-imx

This is the 4.9.220 stable release

Conflicts:
	arch/arm/Kconfig.debug
	arch/arm/boot/dts/imx7s.dtsi
	arch/arm/mach-imx/common.h
	arch/arm/mach-imx/cpuidle-imx6q.c
	arch/arm/mach-imx/cpuidle-imx6sx.c
	arch/arm/mach-imx/suspend-imx6.S
	block/blk-core.c
	drivers/crypto/caam/caamalg.c
	drivers/crypto/mxs-dcp.c
	drivers/dma/imx-sdma.c
	drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
	drivers/input/keyboard/imx_keypad.c
	drivers/input/keyboard/snvs_pwrkey.c
	drivers/mmc/host/sdhci.c
	drivers/net/can/flexcan.c
	drivers/net/ethernet/freescale/fec_main.c
	drivers/net/phy/phy_device.c
	drivers/net/wireless/ath/ath10k/pci.c
	drivers/tty/serial/imx.c
	drivers/usb/dwc3/gadget.c
	drivers/usb/host/xhci.c
	include/linux/blkdev.h
	include/linux/cpu.h
	include/linux/platform_data/dma-imx-sdma.h
	kernel/cpu.c
	net/wireless/util.c
	sound/soc/fsl/Kconfig
	sound/soc/fsl/fsl_esai.c
	sound/soc/fsl/fsl_sai.c
	sound/soc/fsl/imx-sgtl5000.c

1 files changed, 29 insertions, 5 deletions

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index f39a7be98fc1..ea3370e205fb 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -74,9 +74,7 @@ void __ptrace_link(struct task_struct *child, struct task_struct *new_parent,
  */
 static void ptrace_link(struct task_struct *child, struct task_struct *new_parent)
 {
-	rcu_read_lock();
-	__ptrace_link(child, new_parent, __task_cred(new_parent));
-	rcu_read_unlock();
+	__ptrace_link(child, new_parent, current_cred());
 }
 
 /**
@@ -258,6 +256,9 @@ static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
 
 static int ptrace_has_cap(struct user_namespace *ns, unsigned int mode)
 {
+	if (mode & PTRACE_MODE_SCHED)
+		return false;
+
 	if (mode & PTRACE_MODE_NOAUDIT)
 		return has_ns_capability_noaudit(current, ns, CAP_SYS_PTRACE);
 	else
@@ -319,15 +320,32 @@ static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 	return -EPERM;
 ok:
 	rcu_read_unlock();
+	/*
+	 * If a task drops privileges and becomes nondumpable (through a syscall
+	 * like setresuid()) while we are trying to access it, we must ensure
+	 * that the dumpability is read after the credentials; otherwise,
+	 * we may be able to attach to a task that we shouldn't be able to
+	 * attach to (as if the task had dropped privileges without becoming
+	 * nondumpable).
+	 * Pairs with a write barrier in commit_creds().
+	 */
+	smp_rmb();
 	mm = task->mm;
 	if (mm &&
 	    ((get_dumpable(mm) != SUID_DUMP_USER) &&
 	     !ptrace_has_cap(mm->user_ns, mode)))
 	    return -EPERM;
 
+	if (mode & PTRACE_MODE_SCHED)
+		return 0;
 	return security_ptrace_access_check(task, mode);
 }
 
+bool ptrace_may_access_sched(struct task_struct *task, unsigned int mode)
+{
+	return __ptrace_may_access(task, mode | PTRACE_MODE_SCHED);
+}
+
 bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 {
 	int err;
@@ -700,6 +718,10 @@ static int ptrace_peek_siginfo(struct task_struct *child,
 	if (arg.nr < 0)
 		return -EINVAL;
 
+	/* Ensure arg.off fits in an unsigned long */
+	if (arg.off > ULONG_MAX)
+		return 0;
+
 	if (arg.flags & PTRACE_PEEKSIGINFO_SHARED)
 		pending = &child->signal->shared_pending;
 	else
@@ -707,18 +729,20 @@ static int ptrace_peek_siginfo(struct task_struct *child,
 
 	for (i = 0; i < arg.nr; ) {
 		siginfo_t info;
-		s32 off = arg.off + i;
+		unsigned long off = arg.off + i;
+		bool found = false;
 
 		spin_lock_irq(&child->sighand->siglock);
 		list_for_each_entry(q, &pending->list, list) {
 			if (!off--) {
+				found = true;
 				copy_siginfo(&info, &q->info);
 				break;
 			}
 		}
 		spin_unlock_irq(&child->sighand->siglock);
 
-		if (off >= 0) /* beyond the end of the list */
+		if (!found) /* beyond the end of the list */
 			break;
 
 #ifdef CONFIG_COMPAT