lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Wed, 21 Oct 2015 06:22:13 -0700 (PDT) From: David Miller <davem@...emloft.net> To: sowmini.varadhan@...cle.com Cc: steffen.klassert@...unet.com, linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org, netdev@...r.kernel.org, herbert@...dor.apana.org.au, dhowells@...hat.com, zohar@...ux.vnet.ibm.com, David.Woodhouse@...el.com Subject: Re: [PATCH net-next 2/2] xfrm: Fix unaligned access in xfrm_notify_sa() for DELSA From: Sowmini Varadhan <sowmini.varadhan@...cle.com> Date: Wed, 21 Oct 2015 08:36:28 -0400 > + memcpy((u8 *)p, &tmp, sizeof(tmp)); memcpy() _never_ works for avoiding unaligned accessed. I repeat, no matter what you do, no matter what kinds of casts or fancy typing you use, memcpy() _never_ works for this purpose. The compiler knows that the pointer you are using is supposed to be at least 8 byte aligned, it can look through the cast and that's completely legitimate for it to do. So it can legitimately inline emit loads and stores to implement the memcpy() and those will still get the unaligned accesses. There is one and only one portable way to access unaligned data, and that is with the get_unaligned() and put_unaligned() helpers. Userland must do something similar to deal with this situation as well. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists