coredump: fix memleak in dump_vma_snapshot()

dump_vma_snapshot() allocs memory for *vma_meta, when dump_vma_snapshot()
returns -EFAULT, the memory will be leaked, so we free it correctly.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: a07279c ("binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot")
Signed-off-by: QiuXi <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: QiuXi

fs/coredump.c

@@ -1134,8 +1134,10 @@ int dump_vma_snapshot(struct coredump_params *cprm, int *vma_count,
 
 	mmap_write_unlock(mm);
 
-	if (WARN_ON(i != *vma_count))
+	if (WARN_ON(i != *vma_count)) {
+		kvfree(*vma_meta);
 		return -EFAULT;
+	}
 
 	*vma_data_size_ptr = vma_data_size;
 	return 0;