vfs: allocate page instead of names_cache buffer in mount_block_root
First, it's incorrect to call putname() after __getname_gfp() since the
bare __getname_gfp() call skips the auditing code, while putname()
doesn't.
mount_block_root allocates a PATH_MAX buffer via __getname_gfp, and then
calls get_fs_names to fill the buffer. That function can call
get_filesystem_list which assumes that that buffer is a full page in
size. On arches where PAGE_SIZE != 4k, then this could potentially
overrun.
In practice, it's hard to imagine the list of filesystem names even
approaching 4k, but it's best to be safe. Just allocate a page for this
purpose instead.
With this, we can also remove the __getname_gfp() definition since there
are no more callers.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 8ef2fc9..b44b4ca 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2228,8 +2228,7 @@
extern struct kmem_cache *names_cachep;
-#define __getname_gfp(gfp) kmem_cache_alloc(names_cachep, (gfp))
-#define __getname() __getname_gfp(GFP_KERNEL)
+#define __getname() kmem_cache_alloc(names_cachep, GFP_KERNEL)
#define __putname(name) kmem_cache_free(names_cachep, (void *)(name))
#ifndef CONFIG_AUDITSYSCALL
#define putname(name) __putname(name)
