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/init/do_mounts.c b/init/do_mounts.c
index d3f0aee..f8a6642 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -353,8 +353,9 @@
void __init mount_block_root(char *name, int flags)
{
- char *fs_names = __getname_gfp(GFP_KERNEL
- | __GFP_NOTRACK_FALSE_POSITIVE);
+ struct page *page = alloc_page(GFP_KERNEL |
+ __GFP_NOTRACK_FALSE_POSITIVE);
+ char *fs_names = page_address(page);
char *p;
#ifdef CONFIG_BLOCK
char b[BDEVNAME_SIZE];
@@ -406,7 +407,7 @@
#endif
panic("VFS: Unable to mount root fs on %s", b);
out:
- putname(fs_names);
+ put_page(page);
}
#ifdef CONFIG_ROOT_NFS