From: Jeff Layton <jlayton@redhat.com>
To: viro@zeniv.linux.org.uk
Cc: eparis@redhat.com, linux-audit@redhat.com,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v1 01/10] vfs: allocate page instead of names_cache buffer in mount_block_root
Date: Fri, 7 Sep 2012 09:37:56 -0400 [thread overview]
Message-ID: <1347025085-20285-2-git-send-email-jlayton@redhat.com> (raw)
In-Reply-To: <1347025085-20285-1-git-send-email-jlayton@redhat.com>
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>
---
include/linux/fs.h | 3 +--
init/do_mounts.c | 7 ++++---
2 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index aa11047..69513a7 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2221,8 +2221,7 @@ extern void __init vfs_caches_init(unsigned long);
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)
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 @@ static int __init do_mount_root(char *name, char *fs, int flags, void *data)
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 @@ retry:
#endif
panic("VFS: Unable to mount root fs on %s", b);
out:
- putname(fs_names);
+ put_page(page);
}
#ifdef CONFIG_ROOT_NFS
--
1.7.11.4
next prev parent reply other threads:[~2012-09-07 13:41 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-07 13:37 [PATCH v1 00/10] vfs: getname/putname overhaul Jeff Layton
2012-09-07 13:37 ` Jeff Layton [this message]
2012-09-07 13:37 ` [PATCH v1 02/10] vfs: make dir_name arg to do_mount a const char * Jeff Layton
2012-09-07 13:37 ` [PATCH v1 03/10] acct: constify the name arg to acct_on Jeff Layton
2012-09-07 13:37 ` [PATCH v1 04/10] vfs: define getname_info struct and have getname() return it Jeff Layton
2012-09-07 13:38 ` [PATCH v1 05/10] audit: allow audit code to satisfy getname requests from its names_list Jeff Layton
2012-09-07 13:38 ` [PATCH v1 06/10] vfs: turn do_path_lookup into wrapper around getname_info variant Jeff Layton
2012-09-07 13:38 ` [PATCH v1 07/10] vfs: make path_openat take a getname_info pointer Jeff Layton
2012-09-07 13:38 ` [PATCH v1 08/10] audit: make audit_inode take getname_info Jeff Layton
2012-09-07 13:38 ` [PATCH v1 09/10] vfs: embed getname_info inside of names_cache allocation if possible Jeff Layton
2012-09-07 13:38 ` [PATCH v1 10/10] vfs: unexport getname and putname symbols Jeff Layton
2012-09-07 21:26 ` [PATCH v1 00/10] vfs: getname/putname overhaul Andi Kleen
2012-09-08 0:54 ` Jeff Layton
2012-09-08 3:08 ` Andi Kleen
2012-09-08 11:24 ` Jeff Layton
2012-09-08 15:38 ` Andi Kleen
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