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| author | Jeff Layton <jlayton@redhat.com> | 2012-10-10 23:25:26 +0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2012-10-12 08:32:03 +0400 |
| commit | a608ca21f58ee44df5a71ba140e98498f3ebc2cd (patch) | |
| tree | 4ba6f5d5414ba9b579c8e41eb30c21a709537922 | |
| parent | 4fa6b5ecbf092c6ee752ece8a55d71f663d23254 (diff) | |
| download | linux-a608ca21f58ee44df5a71ba140e98498f3ebc2cd.tar.xz | |
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>
| -rw-r--r-- | include/linux/fs.h | 3 | ||||
| -rw-r--r-- | 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 8ef2fc9f1f08..b44b4ca82164 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2228,8 +2228,7 @@ 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 d3f0aeed2d39..f8a66424360d 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 |