Messages in this thread | | | Date | Wed, 15 Mar 2023 16:34:38 +0100 | From | Ahmad Fatoum <> | Subject | Re: [PATCH net 1/2] net: dsa: realtek: fix out-of-bounds access |
| |
Hi Linus,
On 15.03.23 14:15, Linus Walleij wrote: > On Wed, Mar 15, 2023 at 2:09 PM Ahmad Fatoum <a.fatoum@pengutronix.de> wrote: > >> The probe function sets priv->chip_data to (void *)priv + sizeof(*priv) >> with the expectation that priv has enough trailing space. >> >> However, only realtek-smi actually allocated this chip_data space. >> Do likewise in realtek-mdio to fix out-of-bounds accesses. >> >> Fixes: aac94001067d ("net: dsa: realtek: add new mdio interface for drivers") >> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de> > > Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Thanks for the review.
> That this worked for so long is kind of scary, and the reason why we run Kasan > over so much code, I don't know if Kasan would have found this one.
It still worked. I looked into it some more and for some reason, struct realtek_priv has a char buf[4096] member that's unused. I assume it caused kmalloc to return a 8K slab, where the out-of-bound writes didn't overwrite anything of value. That buffer ought to be removed, but that's for net-next.
I just checked with KASAN and it does detect the OOB on ARM64. I first noticed the bug on barebox though, which has a near verbatim port of the Linux driver, but a TLSF allocator, which fits allocations more tightly, hence it crashes not long after driver probe unlike Linux.
> Rewriting the whole world in Rust will fix this problem, but it will > take a while...
^^'.
Cheers, Ahmad
> > Yours, > Linus Walleij >
-- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
| |