Revert "coredump: Use the vma snapshot in fill_files_note"

This reverts commit 558564d.

It breaks the abi and is not needed for Android devices so it can be
dropped.

Bug: 161946584
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I439e74ddf123b2e4d573f490b3c5ba16a08f2d9b

fs/binfmt_elf.c

@@ -1613,16 +1613,17 @@ static void fill_siginfo_note(struct memelfnote *note, user_siginfo_t *csigdata,
  *   long file_ofs
  * followed by COUNT filenames in ASCII: "FILE1" NUL "FILE2" NUL...
  */
-static int fill_files_note(struct memelfnote *note, struct coredump_params *cprm)
+static int fill_files_note(struct memelfnote *note)
 {
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
 	unsigned count, size, names_ofs, remaining, n;
 	user_long_t *data;
 	user_long_t *start_end_ofs;
 	char *name_base, *name_curpos;
-	int i;
 
 	/* *Estimated* file count and total data size needed */
-	count = cprm->vma_count;
+	count = mm->map_count;
 	if (count > UINT_MAX / 64)
 		return -EINVAL;
 	size = count * 64;
@@ -1644,12 +1645,11 @@ static int fill_files_note(struct memelfnote *note, struct coredump_params *cprm
 	name_base = name_curpos = ((char *)data) + names_ofs;
 	remaining = size - names_ofs;
 	count = 0;
-	for (i = 0; i < cprm->vma_count; i++) {
-		struct core_vma_metadata *m = &cprm->vma_meta[i];
+	for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
 		struct file *file;
 		const char *filename;
 
-		file = m->file;
+		file = vma->vm_file;
 		if (!file)
 			continue;
 		filename = file_path(file, name_curpos, remaining);
@@ -1669,9 +1669,9 @@ static int fill_files_note(struct memelfnote *note, struct coredump_params *cprm
 		memmove(name_curpos, filename, n);
 		name_curpos += n;
 
-		*start_end_ofs++ = m->start;
-		*start_end_ofs++ = m->end;
-		*start_end_ofs++ = m->pgoff;
+		*start_end_ofs++ = vma->vm_start;
+		*start_end_ofs++ = vma->vm_end;
+		*start_end_ofs++ = vma->vm_pgoff;
 		count++;
 	}
 
@@ -1682,7 +1682,7 @@ static int fill_files_note(struct memelfnote *note, struct coredump_params *cprm
 	 * Count usually is less than mm->map_count,
 	 * we need to move filenames down.
 	 */
-	n = cprm->vma_count - count;
+	n = mm->map_count - count;
 	if (n != 0) {
 		unsigned shift_bytes = n * 3 * sizeof(data[0]);
 		memmove(name_base - shift_bytes, name_base,
@@ -1884,7 +1884,7 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
 	fill_auxv_note(&info->auxv, current->mm);
 	info->size += notesize(&info->auxv);
 
-	if (fill_files_note(&info->files, cprm) == 0)
+	if (fill_files_note(&info->files) == 0)
 		info->size += notesize(&info->files);
 
 	return 1;
@@ -2073,7 +2073,7 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
 	fill_auxv_note(info->notes + 3, current->mm);
 	info->numnote = 4;
 
-	if (fill_files_note(info->notes + info->numnote, cprm) == 0) {
+	if (fill_files_note(info->notes + info->numnote) == 0) {
 		info->notes_files = info->notes + info->numnote;
 		info->numnote++;
 	}

fs/coredump.c

@@ -54,7 +54,6 @@
 #include <trace/events/sched.h>
 
 static bool dump_vma_snapshot(struct coredump_params *cprm);
-static void free_vma_snapshot(struct coredump_params *cprm);
 
 int core_uses_pid;
 unsigned int core_pipe_limit;
@@ -817,7 +816,7 @@ void do_coredump(const kernel_siginfo_t *siginfo)
 		file_start_write(cprm.file);
 		core_dumped = binfmt->core_dump(&cprm);
 		file_end_write(cprm.file);
-		free_vma_snapshot(&cprm);
+		kvfree(cprm.vma_meta);
 	}
 	if (ispipe && core_pipe_limit)
 		wait_for_dump_helpers(cprm.file);
@@ -1089,20 +1088,6 @@ 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.
@@ -1139,11 +1124,6 @@ static bool dump_vma_snapshot(struct coredump_params *cprm)
 		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;
-
-		m->file = vma->vm_file;
-		if (m->file)
-			get_file(m->file);
 	}
 
 	mmap_write_unlock(mm);

include/linux/coredump.h

@@ -11,8 +11,6 @@ struct core_vma_metadata {
 	unsigned long start, end;
 	unsigned long flags;
 	unsigned long dump_size;
-	unsigned long pgoff;
-	struct file   *file;
 };
 
 /*