Merge tag 'execve-v5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull execve updates from Kees Cook:
 "Execve and binfmt updates.

  Eric and I have stepped up to be the active maintainers of this area,
  so here's our first collection. The bulk of the work was in coredump
  handling fixes; additional details are noted below:

   - Handle unusual AT_PHDR offsets (Akira Kawata)

   - Fix initial mapping size when PT_LOADs are not ordered (Alexey
     Dobriyan)

   - Move more code under CONFIG_COREDUMP (Alexey Dobriyan)

   - Fix missing mmap_lock in file_files_note (Eric W. Biederman)

   - Remove a.out support for alpha and m68k (Eric W. Biederman)

   - Include first pages of non-exec ELF libraries in coredump (Jann
     Horn)

   - Don't write past end of notes for regset gap in coredump (Rick
     Edgecombe)

   - Comment clean-ups (Tom Rix)

   - Force single empty string when argv is empty (Kees Cook)

   - Add NULL argv selftest (Kees Cook)

   - Properly redefine PT_GNU_* in terms of PT_LOOS (Kees Cook)

   - MAINTAINERS: Update execve entry with tree (Kees Cook)

   - Introduce initial KUnit testing for binfmt_elf (Kees Cook)"

* tag 'execve-v5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  binfmt_elf: Don't write past end of notes for regset gap
  a.out: Stop building a.out/osf1 support on alpha and m68k
  coredump: Don't compile flat_core_dump when coredumps are disabled
  coredump: Use the vma snapshot in fill_files_note
  coredump/elf: Pass coredump_params into fill_note_info
  coredump: Remove the WARN_ON in dump_vma_snapshot
  coredump: Snapshot the vmas in do_coredump
  coredump: Move definition of struct coredump_params into coredump.h
  binfmt_elf: Introduce KUnit test
  ELF: Properly redefine PT_GNU_* in terms of PT_LOOS
  MAINTAINERS: Update execve entry with more details
  exec: cleanup comments
  fs/binfmt_elf: Refactor load_elf_binary function
  fs/binfmt_elf: Fix AT_PHDR for unusual ELF files
  binfmt: move more stuff undef CONFIG_COREDUMP
  selftests/exec: Test for empty string on NULL argv
  exec: Force single empty string when argv is empty
  coredump: Also dump first pages of non-executable ELF libraries
  ELF: fix overflow in total mapping size calculation

MAINTAINERS

@@ -7234,6 +7234,9 @@ F:	net/core/of_net.c
 EXEC & BINFMT API
 R:	Eric Biederman <ebiederm@xmission.com>
 R:	Kees Cook <keescook@chromium.org>
+L:	linux-mm@kvack.org
+S:	Supported
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/execve
 F:	arch/alpha/kernel/binfmt_loader.c
 F:	arch/x86/ia32/ia32_aout.c
 F:	fs/*binfmt_*.c
@@ -7241,6 +7244,7 @@ F:	fs/exec.c
 F:	include/linux/binfmts.h
 F:	include/linux/elf.h
 F:	include/uapi/linux/binfmts.h
+F:	include/uapi/linux/elf.h
 F:	tools/testing/selftests/exec/
 N:	asm/elf.h
 N:	binfmt

arch/alpha/Kconfig

@@ -12,7 +12,6 @@ config ALPHA
 	select FORCE_PCI if !ALPHA_JENSEN
 	select PCI_DOMAINS if PCI
 	select PCI_SYSCALL if PCI
-	select HAVE_AOUT
 	select HAVE_ASM_MODVERSIONS
 	select HAVE_PCSPKR_PLATFORM
 	select HAVE_PERF_EVENTS

arch/m68k/Kconfig

@@ -17,7 +17,6 @@ config M68K
 	select GENERIC_CPU_DEVICES
 	select GENERIC_IOMAP
 	select GENERIC_IRQ_SHOW
-	select HAVE_AOUT if MMU
 	select HAVE_ASM_MODVERSIONS
 	select HAVE_DEBUG_BUGVERBOSE
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS if !CPU_HAS_NO_UNALIGNED

fs/Kconfig.binfmt

@@ -28,6 +28,16 @@ config BINFMT_ELF
 	  ld.so (check the file <file:Documentation/Changes> for location and
 	  latest version).
 
+config BINFMT_ELF_KUNIT_TEST
+	bool "Build KUnit tests for ELF binary support" if !KUNIT_ALL_TESTS
+	depends on KUNIT=y && BINFMT_ELF=y
+	default KUNIT_ALL_TESTS
+	help
+	  This builds the ELF loader KUnit tests, which try to gather
+	  prior bug fixes into a regression test collection. This is really
+	  only needed for debugging. Note that with CONFIG_COMPAT=y, the
+	  compat_binfmt_elf KUnit test is also created.
+
 config COMPAT_BINFMT_ELF
 	def_bool y
 	depends on COMPAT && BINFMT_ELF

fs/binfmt_elf_fdpic.c

@@ -83,8 +83,8 @@ static struct linux_binfmt elf_fdpic_format = {
 	.load_binary	= load_elf_fdpic_binary,
 #ifdef CONFIG_ELF_CORE
 	.core_dump	= elf_fdpic_core_dump,
-#endif
 	.min_coredump	= ELF_EXEC_PAGESIZE,
+#endif
 };
 
 static int __init init_elf_fdpic_binfmt(void)
@@ -1465,7 +1465,7 @@ static bool elf_fdpic_dump_segments(struct coredump_params *cprm,
 static int elf_fdpic_core_dump(struct coredump_params *cprm)
 {
 	int has_dumped = 0;
-	int vma_count, segs;
+	int segs;
 	int i;
 	struct elfhdr *elf = NULL;
 	loff_t offset = 0, dataoff;
@@ -1480,8 +1480,6 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
 	elf_addr_t e_shoff;
 	struct core_thread *ct;
 	struct elf_thread_status *tmp;
-	struct core_vma_metadata *vma_meta = NULL;
-	size_t vma_data_size;
 
 	/* alloc memory for large data structures: too large to be on stack */
 	elf = kmalloc(sizeof(*elf), GFP_KERNEL);
@@ -1491,9 +1489,6 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
 	if (!psinfo)
 		goto end_coredump;
 
-	if (dump_vma_snapshot(cprm, &vma_count, &vma_meta, &vma_data_size))
-		goto end_coredump;
-
 	for (ct = current->signal->core_state->dumper.next;
 					ct; ct = ct->next) {
 		tmp = elf_dump_thread_status(cprm->siginfo->si_signo,
@@ -1513,7 +1508,7 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
 	tmp->next = thread_list;
 	thread_list = tmp;
 
-	segs = vma_count + elf_core_extra_phdrs();
+	segs = cprm->vma_count + elf_core_extra_phdrs();
 
 	/* for notes section */
 	segs++;
@@ -1558,7 +1553,7 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
 	/* Page-align dumped data */
 	dataoff = offset = roundup(offset, ELF_EXEC_PAGESIZE);
 
-	offset += vma_data_size;
+	offset += cprm->vma_data_size;
 	offset += elf_core_extra_data_size();
 	e_shoff = offset;
 
@@ -1578,8 +1573,8 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
 		goto end_coredump;
 
 	/* write program headers for segments dump */
-	for (i = 0; i < vma_count; i++) {
-		struct core_vma_metadata *meta = vma_meta + i;
+	for (i = 0; i < cprm->vma_count; i++) {
+		struct core_vma_metadata *meta = cprm->vma_meta + i;
 		struct elf_phdr phdr;
 		size_t sz;
 
@@ -1628,7 +1623,7 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
 
 	dump_skip_to(cprm, dataoff);
 
-	if (!elf_fdpic_dump_segments(cprm, vma_meta, vma_count))
+	if (!elf_fdpic_dump_segments(cprm, cprm->vma_meta, cprm->vma_count))
 		goto end_coredump;
 
 	if (!elf_core_write_extra_data(cprm))
@@ -1652,7 +1647,6 @@ static int elf_fdpic_core_dump(struct coredump_params *cprm)
 		thread_list = thread_list->next;
 		kfree(tmp);
 	}
-	kvfree(vma_meta);
 	kfree(phdr4note);
 	kfree(elf);
 	kfree(psinfo);

fs/binfmt_elf_test.c

+// SPDX-License-Identifier: GPL-2.0-only
+#include <kunit/test.h>
+
+static void total_mapping_size_test(struct kunit *test)
+{
+	struct elf_phdr empty[] = {
+		{ .p_type = PT_LOAD, .p_vaddr = 0, .p_memsz = 0, },
+		{ .p_type = PT_INTERP, .p_vaddr = 10, .p_memsz = 999999, },
+	};
+	/*
+	 * readelf -lW /bin/mount | grep '^  .*0x0' | awk '{print "\t\t{ .p_type = PT_" \
+	 *				$1 ", .p_vaddr = " $3 ", .p_memsz = " $6 ", },"}'
+	 */
+	struct elf_phdr mount[] = {
+		{ .p_type = PT_PHDR, .p_vaddr = 0x00000040, .p_memsz = 0x0002d8, },
+		{ .p_type = PT_INTERP, .p_vaddr = 0x00000318, .p_memsz = 0x00001c, },
+		{ .p_type = PT_LOAD, .p_vaddr = 0x00000000, .p_memsz = 0x0033a8, },
+		{ .p_type = PT_LOAD, .p_vaddr = 0x00004000, .p_memsz = 0x005c91, },
+		{ .p_type = PT_LOAD, .p_vaddr = 0x0000a000, .p_memsz = 0x0022f8, },
+		{ .p_type = PT_LOAD, .p_vaddr = 0x0000d330, .p_memsz = 0x000d40, },
+		{ .p_type = PT_DYNAMIC, .p_vaddr = 0x0000d928, .p_memsz = 0x000200, },
+		{ .p_type = PT_NOTE, .p_vaddr = 0x00000338, .p_memsz = 0x000030, },
+		{ .p_type = PT_NOTE, .p_vaddr = 0x00000368, .p_memsz = 0x000044, },
+		{ .p_type = PT_GNU_PROPERTY, .p_vaddr = 0x00000338, .p_memsz = 0x000030, },
+		{ .p_type = PT_GNU_EH_FRAME, .p_vaddr = 0x0000b490, .p_memsz = 0x0001ec, },
+		{ .p_type = PT_GNU_STACK, .p_vaddr = 0x00000000, .p_memsz = 0x000000, },
+		{ .p_type = PT_GNU_RELRO, .p_vaddr = 0x0000d330, .p_memsz = 0x000cd0, },
+	};
+	size_t mount_size = 0xE070;
+	/* https://lore.kernel.org/linux-fsdevel/YfF18Dy85mCntXrx@fractal.localdomain */
+	struct elf_phdr unordered[] = {
+		{ .p_type = PT_LOAD, .p_vaddr = 0x00000000, .p_memsz = 0x0033a8, },
+		{ .p_type = PT_LOAD, .p_vaddr = 0x0000d330, .p_memsz = 0x000d40, },
+		{ .p_type = PT_LOAD, .p_vaddr = 0x00004000, .p_memsz = 0x005c91, },
+		{ .p_type = PT_LOAD, .p_vaddr = 0x0000a000, .p_memsz = 0x0022f8, },
+	};
+
+	/* No headers, no size. */
+	KUNIT_EXPECT_EQ(test, total_mapping_size(NULL, 0), 0);
+	KUNIT_EXPECT_EQ(test, total_mapping_size(empty, 0), 0);
+	/* Empty headers, no size. */
+	KUNIT_EXPECT_EQ(test, total_mapping_size(empty, 1), 0);
+	/* No PT_LOAD headers, no size. */
+	KUNIT_EXPECT_EQ(test, total_mapping_size(&empty[1], 1), 0);
+	/* Empty PT_LOAD and non-PT_LOAD headers, no size. */
+	KUNIT_EXPECT_EQ(test, total_mapping_size(empty, 2), 0);
+
+	/* Normal set of PT_LOADS, and expected size. */
+	KUNIT_EXPECT_EQ(test, total_mapping_size(mount, ARRAY_SIZE(mount)), mount_size);
+	/* Unordered PT_LOADs result in same size. */
+	KUNIT_EXPECT_EQ(test, total_mapping_size(unordered, ARRAY_SIZE(unordered)), mount_size);
+}
+
+static struct kunit_case binfmt_elf_test_cases[] = {
+	KUNIT_CASE(total_mapping_size_test),
+	{},
+};
+
+static struct kunit_suite binfmt_elf_test_suite = {
+	.name = KBUILD_MODNAME,
+	.test_cases = binfmt_elf_test_cases,
+};
+
+kunit_test_suite(binfmt_elf_test_suite);

fs/binfmt_flat.c

@@ -37,6 +37,7 @@
 #include <linux/flat.h>
 #include <linux/uaccess.h>
 #include <linux/vmalloc.h>
+#include <linux/coredump.h>
 
 #include <asm/byteorder.h>
 #include <asm/unaligned.h>
@@ -97,13 +98,17 @@ static int load_flat_shared_library(int id, struct lib_info *p);
 #endif
 
 static int load_flat_binary(struct linux_binprm *);
+#ifdef CONFIG_COREDUMP
 static int flat_core_dump(struct coredump_params *cprm);
+#endif
 
 static struct linux_binfmt flat_format = {
 	.module		= THIS_MODULE,
 	.load_binary	= load_flat_binary,
+#ifdef CONFIG_COREDUMP
 	.core_dump	= flat_core_dump,
 	.min_coredump	= PAGE_SIZE
+#endif
 };
 
 /****************************************************************************/
@@ -112,12 +117,14 @@ static struct linux_binfmt flat_format = {
  * Currently only a stub-function.
  */
 
+#ifdef CONFIG_COREDUMP
 static int flat_core_dump(struct coredump_params *cprm)
 {
 	pr_warn("Process %s:%d received signr %d and should have core dumped\n",
 		current->comm, current->pid, cprm->siginfo->si_signo);
 	return 1;
 }
+#endif
 
 /****************************************************************************/
 /*

fs/compat_binfmt_elf.c

@@ -135,6 +135,8 @@
 #define elf_format		compat_elf_format
 #define init_elf_binfmt		init_compat_elf_binfmt
 #define exit_elf_binfmt		exit_compat_elf_binfmt
+#define binfmt_elf_test_cases	compat_binfmt_elf_test_cases
+#define binfmt_elf_test_suite	compat_binfmt_elf_test_suite
 
 /*
  * We share all the actual code with the native (64-bit) version.

fs/coredump.c

@@ -42,6 +42,7 @@
 #include <linux/path.h>
 #include <linux/timekeeping.h>
 #include <linux/sysctl.h>
+#include <linux/elf.h>
 
 #include <linux/uaccess.h>
 #include <asm/mmu_context.h>
@@ -53,6 +54,9 @@
 
 #include <trace/events/sched.h>
 
+static bool dump_vma_snapshot(struct coredump_params *cprm);
+static void free_vma_snapshot(struct coredump_params *cprm);
+
 static int core_uses_pid;
 static unsigned int core_pipe_limit;
 static char core_pattern[CORENAME_MAX_SIZE] = "core";
@@ -531,6 +535,7 @@ void do_coredump(const kernel_siginfo_t *siginfo)
 		 * by any locks.
 		 */
 		.mm_flags = mm->flags,
+		.vma_meta = NULL,
 	};
 
 	audit_core_dumps(siginfo->si_signo);
@@ -745,6 +750,9 @@ void do_coredump(const kernel_siginfo_t *siginfo)
 			pr_info("Core dump to |%s disabled\n", cn.corename);
 			goto close_fail;
 		}
+		if (!dump_vma_snapshot(&cprm))
+			goto close_fail;
+
 		file_start_write(cprm.file);
 		core_dumped = binfmt->core_dump(&cprm);
 		/*
@@ -758,6 +766,7 @@ void do_coredump(const kernel_siginfo_t *siginfo)
 			dump_emit(&cprm, "", 1);
 		}
 		file_end_write(cprm.file);
+		free_vma_snapshot(&cprm);
 	}
 	if (ispipe && core_pipe_limit)
 		wait_for_dump_helpers(cprm.file);
@@ -980,6 +989,8 @@ static bool always_dump_vma(struct vm_area_struct *vma)
 	return false;
 }
 
+#define DUMP_SIZE_MAYBE_ELFHDR_PLACEHOLDER 1
+
 /*
  * Decide how much of @vma's contents should be included in a core dump.
  */
@@ -1039,10 +1050,21 @@ static unsigned long vma_dump_size(struct vm_area_struct *vma,
 	 * dump the first page to aid in determining what was mapped here.
 	 */
 	if (FILTER(ELF_HEADERS) &&
-	    vma->vm_pgoff == 0 && (vma->vm_flags & VM_READ) &&
-	    (READ_ONCE(file_inode(vma->vm_file)->i_mode) & 0111) != 0)
+	    vma->vm_pgoff == 0 && (vma->vm_flags & VM_READ)) {
+		if ((READ_ONCE(file_inode(vma->vm_file)->i_mode) & 0111) != 0)
 			return PAGE_SIZE;
 
+		/*
+		 * ELF libraries aren't always executable.
+		 * We'll want to check whether the mapping starts with the ELF
+		 * magic, but not now - we're holding the mmap lock,
+		 * so copy_from_user() doesn't work here.
+		 * Use a placeholder instead, and fix it up later in
+		 * dump_vma_snapshot().
+		 */
+		return DUMP_SIZE_MAYBE_ELFHDR_PLACEHOLDER;
+	}
+
 #undef	FILTER
 
 	return 0;
@@ -1078,18 +1100,29 @@ static struct vm_area_struct *next_vma(struct vm_area_struct *this_vma,
 	return gate_vma;
 }
 
+static void free_vma_snapshot(struct coredump_params *cprm)
+{
+	if (cprm->vma_meta) {
+		int i;
+		for (i = 0; i < cprm->vma_count; i++) {
+			struct file *file = cprm->vma_meta[i].file;
+			if (file)
+				fput(file);
+		}
+		kvfree(cprm->vma_meta);
+		cprm->vma_meta = NULL;
+	}
+}
+
 /*
  * Under the mmap_lock, take a snapshot of relevant information about the task's
  * VMAs.
  */
-int dump_vma_snapshot(struct coredump_params *cprm, int *vma_count,
-		      struct core_vma_metadata **vma_meta,
-		      size_t *vma_data_size_ptr)
+static bool dump_vma_snapshot(struct coredump_params *cprm)
 {
 	struct vm_area_struct *vma, *gate_vma;
 	struct mm_struct *mm = current->mm;
 	int i;
-	size_t vma_data_size = 0;
 
 	/*
 	 * Once the stack expansion code is fixed to not change VMA bounds
@@ -1097,36 +1130,51 @@ int dump_vma_snapshot(struct coredump_params *cprm, int *vma_count,
 	 * mmap_lock in read mode.
 	 */
 	if (mmap_write_lock_killable(mm))
-		return -EINTR;
+		return false;
 
+	cprm->vma_data_size = 0;
 	gate_vma = get_gate_vma(mm);
-	*vma_count = mm->map_count + (gate_vma ? 1 : 0);
+	cprm->vma_count = mm->map_count + (gate_vma ? 1 : 0);
 
-	*vma_meta = kvmalloc_array(*vma_count, sizeof(**vma_meta), GFP_KERNEL);
-	if (!*vma_meta) {
+	cprm->vma_meta = kvmalloc_array(cprm->vma_count, sizeof(*cprm->vma_meta), GFP_KERNEL);
+	if (!cprm->vma_meta) {
 		mmap_write_unlock(mm);
-		return -ENOMEM;
+		return false;
 	}
 
 	for (i = 0, vma = first_vma(current, gate_vma); vma != NULL;
 			vma = next_vma(vma, gate_vma), i++) {
-		struct core_vma_metadata *m = (*vma_meta) + i;
+		struct core_vma_metadata *m = cprm->vma_meta + i;
 
 		m->start = vma->vm_start;
 		m->end = vma->vm_end;
 		m->flags = vma->vm_flags;
 		m->dump_size = vma_dump_size(vma, cprm->mm_flags);
+		m->pgoff = vma->vm_pgoff;
 
-		vma_data_size += m->dump_size;
+		m->file = vma->vm_file;
+		if (m->file)
+			get_file(m->file);
 	}
 
 	mmap_write_unlock(mm);
 
-	if (WARN_ON(i != *vma_count)) {
-		kvfree(*vma_meta);
-		return -EFAULT;
+	for (i = 0; i < cprm->vma_count; i++) {
+		struct core_vma_metadata *m = cprm->vma_meta + i;
+
+		if (m->dump_size == DUMP_SIZE_MAYBE_ELFHDR_PLACEHOLDER) {
+			char elfmag[SELFMAG];
+
+			if (copy_from_user(elfmag, (void __user *)m->start, SELFMAG) ||
+					memcmp(elfmag, ELFMAG, SELFMAG) != 0) {
+				m->dump_size = 0;
+			} else {
+				m->dump_size = PAGE_SIZE;
+			}
 		}
 
-	*vma_data_size_ptr = vma_data_size;
-	return 0;
+		cprm->vma_data_size += m->dump_size;
+	}
+
+	return true;
 }

fs/exec.c

@@ -118,7 +118,7 @@ bool path_noexec(const struct path *path)
  * Note that a shared library must be both readable and executable due to
  * security reasons.
  *
- * Also note that we take the address to load from from the file itself.
+ * Also note that we take the address to load from the file itself.
  */
 SYSCALL_DEFINE1(uselib, const char __user *, library)
 {
@@ -495,8 +495,14 @@ static int bprm_stack_limits(struct linux_binprm *bprm)
 	 * the stack. They aren't stored until much later when we can't
 	 * signal to the parent that the child has run out of stack space.
 	 * Instead, calculate it here so it's possible to fail gracefully.
+	 *
+	 * In the case of argc = 0, make sure there is space for adding a
+	 * empty string (which will bump argc to 1), to ensure confused
+	 * userspace programs don't start processing from argv[1], thinking
+	 * argc can never be 0, to keep them from walking envp by accident.
+	 * See do_execveat_common().
 	 */
-	ptr_size = (bprm->argc + bprm->envc) * sizeof(void *);
+	ptr_size = (max(bprm->argc, 1) + bprm->envc) * sizeof(void *);
 	if (limit <= ptr_size)
 		return -E2BIG;
 	limit -= ptr_size;
@@ -536,7 +542,7 @@ static int copy_strings(int argc, struct user_arg_ptr argv,
 		if (!valid_arg_len(bprm, len))
 			goto out;
 
-		/* We're going to work our way backwords. */
+		/* We're going to work our way backwards. */
 		pos = bprm->p;
 		str += len;
 		bprm->p -= len;
@@ -1269,7 +1275,7 @@ int begin_new_exec(struct linux_binprm * bprm)
 
 	/*
 	 * Must be called _before_ exec_mmap() as bprm->mm is
-	 * not visibile until then. This also enables the update
+	 * not visible until then. This also enables the update
 	 * to be lockless.
 	 */
 	retval = set_mm_exe_file(bprm->mm, bprm->file);
@@ -1897,6 +1903,9 @@ static int do_execveat_common(int fd, struct filename *filename,
 	}
 
 	retval = count(argv, MAX_ARG_STRINGS);
+	if (retval == 0)
+		pr_warn_once("process '%s' launched '%s' with NULL argv: empty string added\n",
+			     current->comm, bprm->filename);
 	if (retval < 0)
 		goto out_free;
 	bprm->argc = retval;
@@ -1923,6 +1932,19 @@ static int do_execveat_common(int fd, struct filename *filename,
 	if (retval < 0)
 		goto out_free;
 
+	/*
+	 * When argv is empty, add an empty string ("") as argv[0] to
+	 * ensure confused userspace programs that start processing
+	 * from argv[1] won't end up walking envp. See also
+	 * bprm_stack_limits().
+	 */
+	if (bprm->argc == 0) {
+		retval = copy_string_kernel("", bprm);
+		if (retval < 0)
+			goto out_free;
+		bprm->argc = 1;
+	}
+
 	retval = bprm_execve(bprm, fd, filename, flags);
 out_free:
 	free_bprm(bprm);
@@ -1951,6 +1973,8 @@ int kernel_execve(const char *kernel_filename,
 	}
 
 	retval = count_strings_kernel(argv);
+	if (WARN_ON_ONCE(retval == 0))
+		retval = -EINVAL;
 	if (retval < 0)
 		goto out_free;
 	bprm->argc = retval;

include/linux/binfmts.h

@@ -8,6 +8,7 @@
 #include <uapi/linux/binfmts.h>
 
 struct filename;
+struct coredump_params;
 
 #define CORENAME_MAX_SIZE 128
 
@@ -77,18 +78,6 @@ struct linux_binprm {
 #define BINPRM_FLAGS_PRESERVE_ARGV0_BIT 3
 #define BINPRM_FLAGS_PRESERVE_ARGV0 (1 << BINPRM_FLAGS_PRESERVE_ARGV0_BIT)
 
-/* Function parameter for binfmt->coredump */
-struct coredump_params {
-	const kernel_siginfo_t *siginfo;
-	struct pt_regs *regs;
-	struct file *file;
-	unsigned long limit;
-	unsigned long mm_flags;
-	loff_t written;
-	loff_t pos;
-	loff_t to_skip;
-};
-
 /*
  * This structure defines the functions that are used to load the binary formats that
  * linux accepts.
@@ -98,8 +87,10 @@ struct linux_binfmt {
 	struct module *module;
 	int (*load_binary)(struct linux_binprm *);
 	int (*load_shlib)(struct file *);
+#ifdef CONFIG_COREDUMP
 	int (*core_dump)(struct coredump_params *cprm);
 	unsigned long min_coredump;	/* minimal dump size */
+#endif
 } __randomize_layout;
 
 extern void __register_binfmt(struct linux_binfmt *fmt, int insert);

include/linux/coredump.h

@@ -12,22 +12,34 @@ struct core_vma_metadata {
 	unsigned long start, end;
 	unsigned long flags;
 	unsigned long dump_size;
+	unsigned long pgoff;
+	struct file   *file;
+};
+
+struct coredump_params {
+	const kernel_siginfo_t *siginfo;
+	struct pt_regs *regs;
+	struct file *file;
+	unsigned long limit;
+	unsigned long mm_flags;
+	loff_t written;
+	loff_t pos;
+	loff_t to_skip;
+	int vma_count;
+	size_t vma_data_size;
+	struct core_vma_metadata *vma_meta;
 };
 
 /*
  * These are the only things you should do on a core-file: use only these
  * functions to write out all the necessary info.
  */
-struct coredump_params;
 extern void dump_skip_to(struct coredump_params *cprm, unsigned long to);
 extern void dump_skip(struct coredump_params *cprm, size_t nr);
 extern int dump_emit(struct coredump_params *cprm, const void *addr, int nr);
 extern int dump_align(struct coredump_params *cprm, int align);
 int dump_user_range(struct coredump_params *cprm, unsigned long start,
 		    unsigned long len);
-int dump_vma_snapshot(struct coredump_params *cprm, int *vma_count,
-		      struct core_vma_metadata **vma_meta,
-		      size_t *vma_data_size_ptr);
 extern void do_coredump(const kernel_siginfo_t *siginfo);
 #else
 static inline void do_coredump(const kernel_siginfo_t *siginfo) {}

include/uapi/linux/elf.h

@@ -35,10 +35,11 @@ typedef __s64	Elf64_Sxword;
 #define PT_HIOS    0x6fffffff      /* OS-specific */
 #define PT_LOPROC  0x70000000
 #define PT_HIPROC  0x7fffffff
-#define PT_GNU_EH_FRAME		0x6474e550
-#define PT_GNU_PROPERTY		0x6474e553
-
+#define PT_GNU_EH_FRAME	(PT_LOOS + 0x474e550)
 #define PT_GNU_STACK	(PT_LOOS + 0x474e551)
+#define PT_GNU_RELRO	(PT_LOOS + 0x474e552)
+#define PT_GNU_PROPERTY	(PT_LOOS + 0x474e553)
+
 
 /* ARM MTE memory tag segment type */
 #define PT_ARM_MEMTAG_MTE	(PT_LOPROC + 0x1)

tools/testing/selftests/exec/Makefile

@@ -10,6 +10,7 @@ TEST_GEN_FILES := execveat.symlink execveat.denatured script subdir
 TEST_FILES := Makefile
 
 TEST_GEN_PROGS += recursion-depth
+TEST_GEN_PROGS += null-argv
 
 EXTRA_CLEAN := $(OUTPUT)/subdir.moved $(OUTPUT)/execveat.moved $(OUTPUT)/xxxxx*	\
 	       $(OUTPUT)/S_I*.test

tools/testing/selftests/exec/null-argv.c

+// SPDX-License-Identifier: GPL-2.0-only
+/* Test that empty argvs are swapped out for a single empty string. */
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include "../kselftest.h"
+
+#define FORK(exec)				\
+do {						\
+	pid = fork();				\
+	if (pid == 0) {				\
+		/* Child */			\
+		exec; /* Some kind of exec */	\
+		perror("# " #exec);		\
+		return 1;			\
+	}					\
+	check_result(pid, #exec);		\
+} while (0)
+
+void check_result(pid_t pid, const char *msg)
+{
+	int wstatus;
+
+	if (pid == (pid_t)-1) {
+		perror("# fork");
+		ksft_test_result_fail("fork failed: %s\n", msg);
+		return;
+	}
+	if (waitpid(pid, &wstatus, 0) < 0) {
+		perror("# waitpid");
+		ksft_test_result_fail("waitpid failed: %s\n", msg);
+		return;
+	}
+	if (!WIFEXITED(wstatus)) {
+		ksft_test_result_fail("child did not exit: %s\n", msg);
+		return;
+	}
+	if (WEXITSTATUS(wstatus) != 0) {
+		ksft_test_result_fail("non-zero exit: %s\n", msg);
+		return;
+	}
+	ksft_test_result_pass("%s\n", msg);
+}
+
+int main(int argc, char *argv[], char *envp[])
+{
+	pid_t pid;
+	static char * const args[] = { NULL };
+	static char * const str[] = { "", NULL };
+
+	/* argc counting checks */
+	if (argc < 1) {
+		fprintf(stderr, "# FAIL: saw argc == 0 (old kernel?)\n");
+		return 1;
+	}
+	if (argc != 1) {
+		fprintf(stderr, "# FAIL: unknown argc (%d)\n", argc);
+		return 1;
+	}
+	if (argv[0][0] == '\0') {
+		/* Good, we found a NULL terminated string at argv[0]! */
+		return 0;
+	}
+
+	/* Test runner. */
+	ksft_print_header();
+	ksft_set_plan(5);
+
+	FORK(execve(argv[0], str, NULL));
+	FORK(execve(argv[0], NULL, NULL));
+	FORK(execve(argv[0], NULL, envp));
+	FORK(execve(argv[0], args, NULL));
+	FORK(execve(argv[0], args, envp));
+
+	ksft_exit(ksft_cnt.ksft_pass == ksft_plan);
+}