On 13/06/06, Pekka J Enberg <[email protected]> wrote:
> As far as I understood, Ingo is worried about:
>
> struct s { /* some fields */; char *buf; };
>
> struct s *p = kmalloc(sizeof(struct s) + BUF_SIZE);
> p->buf = p + sizeof(struct s);
>
> Which could lead to false negative due to p->buf pointing to p. However,
> for us to even _find_ p->buf, we would need an incoming pointer _to_ p
> which makes me think this is not a problem in practice. Hmm?
On 6/13/06, Catalin Marinas <[email protected]> wrote:
Not exactly. In the above case, Ingo (and me) is worried about having a incoming pointer (from other block) equal to p->buf and therefore inside the block allocated with kmalloc.
Ah, right, I overlooked that case. But, is it really a leak? That is,
even though we currently don't have a pointer to the beginning fo the
block, we don't know for sure it was a leak. You're now allowed to do:
p = kmalloc(...);
p = p + HDR_SIZE;
/* ... */
kfree(p - HDR_SIZE);
Do you think we should ban the above?
Pekka
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