Merge tag 'hardening-v6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull hardening updates from Kees Cook:
 "As is pretty normal for this tree, there are changes all over the
  place, especially for small fixes, selftest improvements, and improved
  macro usability.

  Some header changes ended up landing via this tree as they depended on
  the string header cleanups. Also, a notable set of changes is the work
  for the reintroduction of the UBSAN signed integer overflow sanitizer
  so that we can continue to make improvements on the compiler side to
  make this sanitizer a more viable future security hardening option.

  Summary:

   - string.h and related header cleanups (Tanzir Hasan, Andy
     Shevchenko)

   - VMCI memcpy() usage and struct_size() cleanups (Vasiliy Kovalev,
     Harshit Mogalapalli)

   - selftests/powerpc: Fix load_unaligned_zeropad build failure
     (Michael Ellerman)

   - hardened Kconfig fragment updates (Marco Elver, Lukas Bulwahn)

   - Handle tail call optimization better in LKDTM (Douglas Anderson)

   - Use long form types in overflow.h (Andy Shevchenko)

   - Add flags param to string_get_size() (Andy Shevchenko)

   - Add Coccinelle script for potential struct_size() use (Jacob
     Keller)

   - Fix objtool corner case under KCFI (Josh Poimboeuf)

   - Drop 13 year old backward compat CAP_SYS_ADMIN check (Jingzi Meng)

   - Add str_plural() helper (Michal Wajdeczko, Kees Cook)

   - Ignore relocations in .notes section

   - Add comments to explain how __is_constexpr() works

   - Fix m68k stack alignment expectations in stackinit Kunit test

   - Convert string selftests to KUnit

   - Add KUnit tests for fortified string functions

   - Improve reporting during fortified string warnings

   - Allow non-type arg to type_max() and type_min()

   - Allow strscpy() to be called with only 2 arguments

   - Add binary mode to leaking_addresses scanner

   - Various small cleanups to leaking_addresses scanner

   - Adding wrapping_*() arithmetic helper

   - Annotate initial signed integer wrap-around in refcount_t

   - Add explicit UBSAN section to MAINTAINERS

   - Fix UBSAN self-test warnings

   - Simplify UBSAN build via removal of CONFIG_UBSAN_SANITIZE_ALL

   - Reintroduce UBSAN's signed overflow sanitizer"

* tag 'hardening-v6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (51 commits)
  selftests/powerpc: Fix load_unaligned_zeropad build failure
  string: Convert helpers selftest to KUnit
  string: Convert selftest to KUnit
  sh: Fix build with CONFIG_UBSAN=y
  compiler.h: Explain how __is_constexpr() works
  overflow: Allow non-type arg to type_max() and type_min()
  VMCI: Fix possible memcpy() run-time warning in vmci_datagram_invoke_guest_handler()
  lib/string_helpers: Add flags param to string_get_size()
  x86, relocs: Ignore relocations in .notes section
  objtool: Fix UNWIND_HINT_{SAVE,RESTORE} across basic blocks
  overflow: Use POD in check_shl_overflow()
  lib: stackinit: Adjust target string to 8 bytes for m68k
  sparc: vdso: Disable UBSAN instrumentation
  kernel.h: Move lib/cmdline.c prototypes to string.h
  leaking_addresses: Provide mechanism to scan binary files
  leaking_addresses: Ignore input device status lines
  leaking_addresses: Use File::Temp for /tmp files
  MAINTAINERS: Update LEAKING_ADDRESSES details
  fortify: Improve buffer overflow reporting
  fortify: Add KUnit tests for runtime overflows
  ...

3 files changed, 22 insertions, 13 deletions

diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c
index b080eb2335eb..b92767d6bdd2 100644
--- a/drivers/misc/lkdtm/bugs.c
+++ b/drivers/misc/lkdtm/bugs.c
@@ -294,10 +294,11 @@ static void lkdtm_SPINLOCKUP(void)
 	__release(&lock_me_up);
 }
 
-static void lkdtm_HUNG_TASK(void)
+static void __noreturn lkdtm_HUNG_TASK(void)
 {
 	set_current_state(TASK_UNINTERRUPTIBLE);
 	schedule();
+	BUG();
 }
 
 static volatile unsigned int huge = INT_MAX - 2;
diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
index 0772e4a4757e..5732fd59a227 100644
--- a/drivers/misc/lkdtm/core.c
+++ b/drivers/misc/lkdtm/core.c
@@ -153,12 +153,17 @@ static const struct crashtype *find_crashtype(const char *name)
 /*
  * This is forced noinline just so it distinctly shows up in the stackdump
  * which makes validation of expected lkdtm crashes easier.
+ *
+ * NOTE: having a valid return value helps prevent the compiler from doing
+ * tail call optimizations and taking this out of the stack trace.
  */
-static noinline void lkdtm_do_action(const struct crashtype *crashtype)
+static noinline int lkdtm_do_action(const struct crashtype *crashtype)
 {
 	if (WARN_ON(!crashtype || !crashtype->func))
-		return;
+		return -EINVAL;
 	crashtype->func();
+
+	return 0;
 }
 
 static int lkdtm_register_cpoint(struct crashpoint *crashpoint,
@@ -167,10 +172,8 @@ static int lkdtm_register_cpoint(struct crashpoint *crashpoint,
 	int ret;
 
 	/* If this doesn't have a symbol, just call immediately. */
-	if (!crashpoint->kprobe.symbol_name) {
-		lkdtm_do_action(crashtype);
-		return 0;
-	}
+	if (!crashpoint->kprobe.symbol_name)
+		return lkdtm_do_action(crashtype);
 
 	if (lkdtm_kprobe != NULL)
 		unregister_kprobe(lkdtm_kprobe);
@@ -216,7 +219,7 @@ static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)
 	spin_unlock_irqrestore(&crash_count_lock, flags);
 
 	if (do_it)
-		lkdtm_do_action(lkdtm_crashtype);
+		return lkdtm_do_action(lkdtm_crashtype);
 
 	return 0;
 }
@@ -303,6 +306,7 @@ static ssize_t direct_entry(struct file *f, const char __user *user_buf,
 {
 	const struct crashtype *crashtype;
 	char *buf;
+	int err;
 
 	if (count >= PAGE_SIZE)
 		return -EINVAL;
@@ -326,9 +330,11 @@ static ssize_t direct_entry(struct file *f, const char __user *user_buf,
 		return -EINVAL;
 
 	pr_info("Performing direct entry %s\n", crashtype->name);
-	lkdtm_do_action(crashtype);
+	err = lkdtm_do_action(crashtype);
 	*off += count;
 
+	if (err)
+		return err;
 	return count;
 }
 
diff --git a/drivers/misc/vmw_vmci/vmci_datagram.c b/drivers/misc/vmw_vmci/vmci_datagram.c
index f50d22882476..3964d9e5a39b 100644
--- a/drivers/misc/vmw_vmci/vmci_datagram.c
+++ b/drivers/misc/vmw_vmci/vmci_datagram.c
@@ -224,8 +224,8 @@ static int dg_dispatch_as_host(u32 context_id, struct vmci_datagram *dg)
 				return VMCI_ERROR_NO_MEM;
 			}
 
-			dg_info = kmalloc(sizeof(*dg_info) +
-				    (size_t) dg->payload_size, GFP_ATOMIC);
+			dg_info = kmalloc(struct_size(dg_info, msg_payload, dg->payload_size),
+					  GFP_ATOMIC);
 			if (!dg_info) {
 				atomic_dec(&delayed_dg_host_queue_size);
 				vmci_resource_put(resource);
@@ -234,7 +234,8 @@ static int dg_dispatch_as_host(u32 context_id, struct vmci_datagram *dg)
 
 			dg_info->in_dg_host_queue = true;
 			dg_info->entry = dst_entry;
-			memcpy(&dg_info->msg, dg, dg_size);
+			dg_info->msg = *dg;
+			memcpy(&dg_info->msg_payload, dg + 1, dg->payload_size);
 
 			INIT_WORK(&dg_info->work, dg_delayed_dispatch);
 			schedule_work(&dg_info->work);
@@ -377,7 +378,8 @@ int vmci_datagram_invoke_guest_handler(struct vmci_datagram *dg)
 
 		dg_info->in_dg_host_queue = false;
 		dg_info->entry = dst_entry;
-		memcpy(&dg_info->msg, dg, VMCI_DG_SIZE(dg));
+		dg_info->msg = *dg;
+		memcpy(&dg_info->msg_payload, dg + 1, dg->payload_size);
 
 		INIT_WORK(&dg_info->work, dg_delayed_dispatch);
 		schedule_work(&dg_info->work);