| Message ID | 20180518200213.GA8006@avx2 (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, May 18, 2018 at 11:02:13PM +0300, Alexey Dobriyan wrote: > Automatically cap sizeof(struct proc_dir_entry) at 192/128 bytes or > 256/192 bytes if spinlock debugging/lockdep is enabled. > --- a/fs/proc/internal.h > +++ b/fs/proc/internal.h > @@ -61,13 +61,15 @@ struct proc_dir_entry { > char *name; > umode_t mode; > u8 namelen; > + char inline_name[]; > +} __randomize_layout; > + Hmm... proc_root initialization relies upon a gccism after that... Speaking of which, why the hell do we even bother with proc_root.name?
On Fri, May 18, 2018 at 09:23:15PM +0100, Al Viro wrote: > On Fri, May 18, 2018 at 11:02:13PM +0300, Alexey Dobriyan wrote: > > Automatically cap sizeof(struct proc_dir_entry) at 192/128 bytes or > > 256/192 bytes if spinlock debugging/lockdep is enabled. > > > --- a/fs/proc/internal.h > > +++ b/fs/proc/internal.h > > @@ -61,13 +61,15 @@ struct proc_dir_entry { > > char *name; > > umode_t mode; > > u8 namelen; > > + char inline_name[]; > > +} __randomize_layout; > > + > > Hmm... proc_root initialization relies upon a gccism after that... Yeah well. > Speaking of which, why the hell do we even bother with proc_root.name? printk("%s/%s", pde->parent->name, pde->name) is nice and doesn't cost anything (OK, it may cost 5 bytes).
--- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -410,7 +410,7 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent, if (!ent) goto out; - if (qstr.len + 1 <= sizeof(ent->inline_name)) { + if (qstr.len + 1 <= SIZEOF_PDE_INLINE_NAME) { ent->name = ent->inline_name; } else { ent->name = kmalloc(qstr.len + 1, GFP_KERNEL); --- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -105,9 +105,10 @@ void __init proc_init_kmemcache(void) kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0, SLAB_ACCOUNT|SLAB_PANIC, NULL); proc_dir_entry_cache = kmem_cache_create_usercopy( - "proc_dir_entry", sizeof(struct proc_dir_entry), 0, SLAB_PANIC, + "proc_dir_entry", SIZEOF_PDE, 0, SLAB_PANIC, offsetof(struct proc_dir_entry, inline_name), - sizeof_field(struct proc_dir_entry, inline_name), NULL); + SIZEOF_PDE_INLINE_NAME, NULL); + BUILD_BUG_ON(sizeof(struct proc_dir_entry) >= SIZEOF_PDE); } static int proc_show_options(struct seq_file *seq, struct dentry *root) --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -61,13 +61,15 @@ struct proc_dir_entry { char *name; umode_t mode; u8 namelen; + char inline_name[]; +} __randomize_layout; + #ifdef CONFIG_64BIT -#define SIZEOF_PDE_INLINE_NAME (192-155) +#define SIZEOF_PDE (sizeof(spinlock_t) == 4 ? 192 : 256) #else -#define SIZEOF_PDE_INLINE_NAME (128-95) +#define SIZEOF_PDE (sizeof(spinlock_t) == 4 ? 128 : 192) #endif - char inline_name[SIZEOF_PDE_INLINE_NAME]; -} __randomize_layout; +#define SIZEOF_PDE_INLINE_NAME (SIZEOF_PDE - sizeof(struct proc_dir_entry)) extern struct kmem_cache *proc_dir_entry_cache; void pde_free(struct proc_dir_entry *pde);
Automatically cap sizeof(struct proc_dir_entry) at 192/128 bytes or 256/192 bytes if spinlock debugging/lockdep is enabled. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> --- fs/proc/generic.c | 2 +- fs/proc/inode.c | 5 +++-- fs/proc/internal.h | 10 ++++++---- 3 files changed, 10 insertions(+), 7 deletions(-)