Re: [Bugme-new] [Bug 33502] New: Caught 64-bit read from uninitialized memory in __alloc_skb

Eric Dumazet
2011-05-10T17:14:47Z

Le mardi 10 mai 2011 à 11:39 -0500, Christoph Lameter a écrit :

> #ifdef CONFIG_DEBUG_PAGE_ALLOC
> if (illegal_page_alloc-address(object))
> goto redo;
> #endif
>
> before the cmpxchg should do the trick.
>

Again, it wont work...

You can have an IRQ right after the check and before cmpxchg

This interrupt can allocate this block of memory, free it, and unmap
page from memory.

cmpxchg() reads unmapped memory -> BUG