On Thu, Apr 30, 2009 at 03:05:42PM +0200, Nick Piggin wrote: [...] > --- > SLQB: fix dumb early allocation cache > > The dumb early allocation cache had a bug where it could allow allocation > to go past the end of a page, which could cause crashes or random memory > corruption. Fix this and simplify the logic. > > Signed-off-by: Nick Piggin <npiggin@xxxxxxx> > --- > mm/slqb.c | 19 +++++++++++-------- > 1 file changed, 11 insertions(+), 8 deletions(-) > > Index: linux-2.6/mm/slqb.c > =================================================================== > --- linux-2.6.orig/mm/slqb.c > +++ linux-2.6/mm/slqb.c > @@ -2185,8 +2185,11 @@ static void *kmem_cache_dyn_array_alloc( > { > size_t size = sizeof(void *) * ids; > > + BUG_ON(!size); > + > if (unlikely(!slab_is_available())) { > static void *nextmem; > + static size_t nextleft; > void *ret; > > /* > @@ -2194,16 +2197,16 @@ static void *kmem_cache_dyn_array_alloc( > * never get freed by definition so we can do it rather > * simply. > */ > - if (!nextmem) { > - nextmem = alloc_pages_exact(size, GFP_KERNEL); > - if (!nextmem) > - return NULL; > + if (size > nextleft) { > + nextmem = alloc_pages_exact(size, GFP_KERNEL); > + if (!nextmem) > + return NULL; Cosmetic issue: spaces instead of tabs are used on these three lines. > + nextleft = roundup(size, PAGE_SIZE); > } > + > ret = nextmem; > - nextmem = (void *)((unsigned long)ret + size); > - if ((unsigned long)ret >> PAGE_SHIFT != > - (unsigned long)nextmem >> PAGE_SHIFT) > - nextmem = NULL; > + nextleft -= size; > + nextmem += size; > memset(ret, 0, size); > return ret; > } else { -- Anton Vorontsov email: cbouatmailru@xxxxxxxxx irc://irc.freenode.net/bd2 -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html