Merge tag 'hardening-v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull hardening updates from Kees Cook:
 "There are three areas of note:

  A bunch of strlcpy()->strscpy() conversions ended up living in my tree
  since they were either Acked by maintainers for me to carry, or got
  ignored for multiple weeks (and were trivial changes).

  The compiler option '-fstrict-flex-arrays=3' has been enabled
  globally, and has been in -next for the entire devel cycle. This
  changes compiler diagnostics (though mainly just -Warray-bounds which
  is disabled) and potential UBSAN_BOUNDS and FORTIFY _warning_
  coverage. In other words, there are no new restrictions, just
  potentially new warnings. Any new FORTIFY warnings we've seen have
  been fixed (usually in their respective subsystem trees). For more
  details, see commit df8fc4e934c12b.

  The under-development compiler attribute __counted_by has been added
  so that we can start annotating flexible array members with their
  associated structure member that tracks the count of flexible array
  elements at run-time. It is possible (likely?) that the exact syntax
  of the attribute will change before it is finalized, but GCC and Clang
  are working together to sort it out. Any changes can be made to the
  macro while we continue to add annotations.

  As an example of that last case, I have a treewide commit waiting with
  such annotations found via Coccinelle:

    https://git.kernel.org/linus/adc5b3cb48a049563dc673f348eab7b6beba8a9b

  Also see commit dd06e72e68bcb4 for more details.

  Summary:

   - Fix KMSAN vs FORTIFY in strlcpy/strlcat (Alexander Potapenko)

   - Convert strreplace() to return string start (Andy Shevchenko)

   - Flexible array conversions (Arnd Bergmann, Wyes Karny, Kees Cook)

   - Add missing function prototypes seen with W=1 (Arnd Bergmann)

   - Fix strscpy() kerndoc typo (Arne Welzel)

   - Replace strlcpy() with strscpy() across many subsystems which were
     either Acked by respective maintainers or were trivial changes that
     went ignored for multiple weeks (Azeem Shaikh)

   - Remove unneeded cc-option test for UBSAN_TRAP (Nick Desaulniers)

   - Add KUnit tests for strcat()-family

   - Enable KUnit tests of FORTIFY wrappers under UML

   - Add more complete FORTIFY protections for strlcat()

   - Add missed disabling of FORTIFY for all arch purgatories.

   - Enable -fstrict-flex-arrays=3 globally

   - Tightening UBSAN_BOUNDS when using GCC

   - Improve checkpatch to check for strcpy, strncpy, and fake flex
     arrays

   - Improve use of const variables in FORTIFY

   - Add requested struct_size_t() helper for types not pointers

   - Add __counted_by macro for annotating flexible array size members"

* tag 'hardening-v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (54 commits)
  netfilter: ipset: Replace strlcpy with strscpy
  uml: Replace strlcpy with strscpy
  um: Use HOST_DIR for mrproper
  kallsyms: Replace all non-returning strlcpy with strscpy
  sh: Replace all non-returning strlcpy with strscpy
  of/flattree: Replace all non-returning strlcpy with strscpy
  sparc64: Replace all non-returning strlcpy with strscpy
  Hexagon: Replace all non-returning strlcpy with strscpy
  kobject: Use return value of strreplace()
  lib/string_helpers: Change returned value of the strreplace()
  jbd2: Avoid printing outside the boundary of the buffer
  checkpatch: Check for 0-length and 1-element arrays
  riscv/purgatory: Do not use fortified string functions
  s390/purgatory: Do not use fortified string functions
  x86/purgatory: Do not use fortified string functions
  acpi: Replace struct acpi_table_slit 1-element array with flex-array
  clocksource: Replace all non-returning strlcpy with strscpy
  string: use __builtin_memcpy() in strlcpy/strlcat
  staging: most: Replace all non-returning strlcpy with strscpy
  drm/i2c: tda998x: Replace all non-returning strlcpy with strscpy
  ...

84 files changed, 467 insertions, 203 deletions

diff --git a/Documentation/filesystems/autofs-mount-control.rst b/Documentation/filesystems/autofs-mount-control.rst
index bf4b511cdbe8..b5a379d25c40 100644
--- a/Documentation/filesystems/autofs-mount-control.rst
+++ b/Documentation/filesystems/autofs-mount-control.rst
@@ -196,7 +196,7 @@ information and return operation results::
 		    struct args_ismountpoint	ismountpoint;
 	    };
 
-	    char path[0];
+	    char path[];
     };
 
 The ioctlfd field is a mount point file descriptor of an autofs mount
diff --git a/Documentation/filesystems/autofs.rst b/Documentation/filesystems/autofs.rst
index 4f490278d22f..3b6e38e646cd 100644
--- a/Documentation/filesystems/autofs.rst
+++ b/Documentation/filesystems/autofs.rst
@@ -467,7 +467,7 @@ Each ioctl is passed a pointer to an `autofs_dev_ioctl` structure::
 			struct args_ismountpoint	ismountpoint;
 		};
 
-                char path[0];
+                char path[];
         };
 
 For the **OPEN_MOUNT** and **IS_MOUNTPOINT** commands, the target
diff --git a/MAINTAINERS b/MAINTAINERS
index c5ad895d6fa4..3e024fac72f5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8099,6 +8099,7 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/har
 F:	include/linux/fortify-string.h
 F:	lib/fortify_kunit.c
 F:	lib/memcpy_kunit.c
+F:	lib/strcat_kunit.c
 F:	lib/strscpy_kunit.c
 F:	lib/test_fortify/*
 F:	scripts/test_fortify.sh
diff --git a/Makefile b/Makefile
index e51e4d9174ab..48a044bfe062 100644
--- a/Makefile
+++ b/Makefile
@@ -1026,6 +1026,12 @@ KBUILD_CFLAGS += -Wno-pointer-sign
 # globally built with -Wcast-function-type.
 KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type)
 
+# To gain proper coverage for CONFIG_UBSAN_BOUNDS and CONFIG_FORTIFY_SOURCE,
+# the kernel uses only C99 flexible arrays for dynamically sized trailing
+# arrays. Enforce this for everything that may examine structure sizes and
+# perform bounds checking.
+KBUILD_CFLAGS += $(call cc-option, -fstrict-flex-arrays=3)
+
 # disable stringop warnings in gcc 8+
 KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
 
diff --git a/arch/hexagon/kernel/setup.c b/arch/hexagon/kernel/setup.c
index 1880d9beaf2b..621674e86232 100644
--- a/arch/hexagon/kernel/setup.c
+++ b/arch/hexagon/kernel/setup.c
@@ -66,9 +66,9 @@ void __init setup_arch(char **cmdline_p)
 		on_simulator = 0;
 
 	if (p[0] != '\0')
-		strlcpy(boot_command_line, p, COMMAND_LINE_SIZE);
+		strscpy(boot_command_line, p, COMMAND_LINE_SIZE);
 	else
-		strlcpy(boot_command_line, default_command_line,
+		strscpy(boot_command_line, default_command_line,
 			COMMAND_LINE_SIZE);
 
 	/*
@@ -76,7 +76,7 @@ void __init setup_arch(char **cmdline_p)
 	 * are both picked up by the init code. If no reason to
 	 * make them different, pass the same pointer back.
 	 */
-	strlcpy(cmd_line, boot_command_line, COMMAND_LINE_SIZE);
+	strscpy(cmd_line, boot_command_line, COMMAND_LINE_SIZE);
 	*cmdline_p = cmd_line;
 
 	parse_early_param();
diff --git a/arch/microblaze/kernel/prom.c b/arch/microblaze/kernel/prom.c
index c5c6186a7e8b..e424c796e297 100644
--- a/arch/microblaze/kernel/prom.c
+++ b/arch/microblaze/kernel/prom.c
@@ -20,7 +20,7 @@ void __init early_init_devtree(void *params)
 
 	early_init_dt_scan(params);
 	if (!strlen(boot_command_line))
-		strlcpy(boot_command_line, cmd_line, COMMAND_LINE_SIZE);
+		strscpy(boot_command_line, cmd_line, COMMAND_LINE_SIZE);
 
 	memblock_allow_resize();
 
diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile
index bd2e27f82532..dc20e166983e 100644
--- a/arch/riscv/purgatory/Makefile
+++ b/arch/riscv/purgatory/Makefile
@@ -31,7 +31,7 @@ $(obj)/strncmp.o: $(srctree)/arch/riscv/lib/strncmp.S FORCE
 $(obj)/sha256.o: $(srctree)/lib/crypto/sha256.c FORCE
 	$(call if_changed_rule,cc_o_c)
 
-CFLAGS_sha256.o := -D__DISABLE_EXPORTS
+CFLAGS_sha256.o := -D__DISABLE_EXPORTS -D__NO_FORTIFY
 CFLAGS_string.o := -D__DISABLE_EXPORTS
 CFLAGS_ctype.o := -D__DISABLE_EXPORTS
 
diff --git a/arch/s390/purgatory/Makefile b/arch/s390/purgatory/Makefile
index cc8cf5abea15..4e930f566878 100644
--- a/arch/s390/purgatory/Makefile
+++ b/arch/s390/purgatory/Makefile
@@ -10,7 +10,7 @@ PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y))
 $(obj)/sha256.o: $(srctree)/lib/crypto/sha256.c FORCE
 	$(call if_changed_rule,cc_o_c)
 
-CFLAGS_sha256.o := -D__DISABLE_EXPORTS
+CFLAGS_sha256.o := -D__DISABLE_EXPORTS -D__NO_FORTIFY
 
 $(obj)/mem.o: $(srctree)/arch/s390/lib/mem.S FORCE
 	$(call if_changed_rule,as_o_S)
diff --git a/arch/sh/drivers/dma/dma-api.c b/arch/sh/drivers/dma/dma-api.c
index ab9170494dcc..89cd4a3b4cca 100644
--- a/arch/sh/drivers/dma/dma-api.c
+++ b/arch/sh/drivers/dma/dma-api.c
@@ -198,7 +198,7 @@ int request_dma(unsigned int chan, const char *dev_id)
 	if (atomic_xchg(&channel->busy, 1))
 		return -EBUSY;
 
-	strlcpy(channel->dev_id, dev_id, sizeof(channel->dev_id));
+	strscpy(channel->dev_id, dev_id, sizeof(channel->dev_id));
 
 	if (info->ops->request) {
 		result = info->ops->request(channel);
diff --git a/arch/sh/kernel/setup.c b/arch/sh/kernel/setup.c
index cf7c0f72f293..b3da2757faaf 100644
--- a/arch/sh/kernel/setup.c
+++ b/arch/sh/kernel/setup.c
@@ -305,9 +305,9 @@ void __init setup_arch(char **cmdline_p)
 	bss_resource.end = virt_to_phys(__bss_stop)-1;
 
 #ifdef CONFIG_CMDLINE_OVERWRITE
-	strlcpy(command_line, CONFIG_CMDLINE, sizeof(command_line));
+	strscpy(command_line, CONFIG_CMDLINE, sizeof(command_line));
 #else
-	strlcpy(command_line, COMMAND_LINE, sizeof(command_line));
+	strscpy(command_line, COMMAND_LINE, sizeof(command_line));
 #ifdef CONFIG_CMDLINE_EXTEND
 	strlcat(command_line, " ", sizeof(command_line));
 	strlcat(command_line, CONFIG_CMDLINE, sizeof(command_line));
diff --git a/arch/sparc/kernel/ioport.c b/arch/sparc/kernel/ioport.c
index 4e4f3d3263e4..a8cbe403301f 100644
--- a/arch/sparc/kernel/ioport.c
+++ b/arch/sparc/kernel/ioport.c
@@ -191,7 +191,7 @@ static void __iomem *_sparc_alloc_io(unsigned int busno, unsigned long phys,
 		tack += sizeof (struct resource);
 	}
 
-	strlcpy(tack, name, XNMLN+1);
+	strscpy(tack, name, XNMLN+1);
 	res->name = tack;
 
 	va = _sparc_ioremap(res, busno, phys, size);
diff --git a/arch/sparc/kernel/setup_32.c b/arch/sparc/kernel/setup_32.c
index c9d1ba4f311b..1adf5c1c16b8 100644
--- a/arch/sparc/kernel/setup_32.c
+++ b/arch/sparc/kernel/setup_32.c
@@ -302,7 +302,7 @@ void __init setup_arch(char **cmdline_p)
 
 	/* Initialize PROM console and command line. */
 	*cmdline_p = prom_getbootargs();
-	strlcpy(boot_command_line, *cmdline_p, COMMAND_LINE_SIZE);
+	strscpy(boot_command_line, *cmdline_p, COMMAND_LINE_SIZE);
 	parse_early_param();
 
 	boot_flags_init(*cmdline_p);
diff --git a/arch/sparc/kernel/setup_64.c b/arch/sparc/kernel/setup_64.c
index 48abee4eee29..6546ca9d4d3f 100644
--- a/arch/sparc/kernel/setup_64.c
+++ b/arch/sparc/kernel/setup_64.c
@@ -636,7 +636,7 @@ void __init setup_arch(char **cmdline_p)
 {
 	/* Initialize PROM console and command line. */
 	*cmdline_p = prom_getbootargs();
-	strlcpy(boot_command_line, *cmdline_p, COMMAND_LINE_SIZE);
+	strscpy(boot_command_line, *cmdline_p, COMMAND_LINE_SIZE);
 	parse_early_param();
 
 	boot_flags_init(*cmdline_p);
diff --git a/arch/sparc/prom/bootstr_32.c b/arch/sparc/prom/bootstr_32.c
index e3b731ff00f0..1c7cd258b0dc 100644
--- a/arch/sparc/prom/bootstr_32.c
+++ b/arch/sparc/prom/bootstr_32.c
@@ -52,7 +52,7 @@ prom_getbootargs(void)
 		 * V3 PROM cannot supply as with more than 128 bytes
 		 * of an argument. But a smart bootstrap loader can.
 		 */
-		strlcpy(barg_buf, *romvec->pv_v2bootargs.bootargs, sizeof(barg_buf));
+		strscpy(barg_buf, *romvec->pv_v2bootargs.bootargs, sizeof(barg_buf));
 		break;
 	default:
 		break;
diff --git a/arch/um/Makefile b/arch/um/Makefile
index 8186d4761bda..da4d5256af2f 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -149,7 +149,7 @@ export CFLAGS_vmlinux := $(LINK-y) $(LINK_WRAPS) $(LD_FLAGS_CMDLINE) $(CC_FLAGS_
 # When cleaning we don't include .config, so we don't include
 # TT or skas makefiles and don't clean skas_ptregs.h.
 CLEAN_FILES += linux x.i gmon.out
-MRPROPER_FILES += arch/$(SUBARCH)/include/generated
+MRPROPER_FILES += $(HOST_DIR)/include/generated
 
 archclean:
 	@find . \( -name '*.bb' -o -name '*.bbg' -o -name '*.da' \
diff --git a/arch/um/include/shared/user.h b/arch/um/include/shared/user.h
index bda66e5a9d4e..0347a190429c 100644
--- a/arch/um/include/shared/user.h
+++ b/arch/um/include/shared/user.h
@@ -52,6 +52,7 @@ static inline int printk(const char *fmt, ...)
 extern int in_aton(char *str);
 extern size_t strlcpy(char *, const char *, size_t);
 extern size_t strlcat(char *, const char *, size_t);
+extern size_t strscpy(char *, const char *, size_t);
 
 /* Copied from linux/compiler-gcc.h since we can't include it directly */
 #define barrier() __asm__ __volatile__("": : :"memory")
diff --git a/arch/um/os-Linux/drivers/tuntap_user.c b/arch/um/os-Linux/drivers/tuntap_user.c
index 53eb3d508645..2284e9c1cbbb 100644
--- a/arch/um/os-Linux/drivers/tuntap_user.c
+++ b/arch/um/os-Linux/drivers/tuntap_user.c
@@ -146,7 +146,7 @@ static int tuntap_open(void *data)
 		}
 		memset(&ifr, 0, sizeof(ifr));
 		ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
-		strlcpy(ifr.ifr_name, pri->dev_name, sizeof(ifr.ifr_name));
+		strscpy(ifr.ifr_name, pri->dev_name, sizeof(ifr.ifr_name));
 		if (ioctl(pri->fd, TUNSETIFF, &ifr) < 0) {
 			err = -errno;
 			printk(UM_KERN_ERR "TUNSETIFF failed, errno = %d\n",
diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index 42abd6af1198..c2a29be35c01 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -12,7 +12,7 @@ $(obj)/string.o: $(srctree)/arch/x86/boot/compressed/string.c FORCE
 $(obj)/sha256.o: $(srctree)/lib/crypto/sha256.c FORCE
 	$(call if_changed_rule,cc_o_c)
 
-CFLAGS_sha256.o := -D__DISABLE_EXPORTS
+CFLAGS_sha256.o := -D__DISABLE_EXPORTS -D__NO_FORTIFY
 
 # When profile-guided optimization is enabled, llvm emits two different
 # overlapping text sections, which is not supported by kexec. Remove profile
diff --git a/drivers/gpu/drm/amd/amdgpu/atom.c b/drivers/gpu/drm/amd/amdgpu/atom.c
index 1c5d9388ad0b..5f610e9a5f0f 100644
--- a/drivers/gpu/drm/amd/amdgpu/atom.c
+++ b/drivers/gpu/drm/amd/amdgpu/atom.c
@@ -1509,7 +1509,7 @@ struct atom_context *amdgpu_atom_parse(struct card_info *card, void *bios)
 	str = CSTR(idx);
 	if (*str != '\0') {
 		pr_info("ATOM BIOS: %s\n", str);
-		strlcpy(ctx->vbios_version, str, sizeof(ctx->vbios_version));
+		strscpy(ctx->vbios_version, str, sizeof(ctx->vbios_version));
 	}
 
 	atom_rom_header = (struct _ATOM_ROM_HEADER *)CSTR(base);
diff --git a/drivers/gpu/drm/amd/pm/legacy-dpm/legacy_dpm.c b/drivers/gpu/drm/amd/