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: Tue, 9 Jan 2018 17:57:14 -0800 From: Alexei Starovoitov <alexei.starovoitov@...il.com> To: Dan Williams <dan.j.williams@...el.com> Cc: Linus Torvalds <torvalds@...ux-foundation.org>, "Eric W. Biederman" <ebiederm@...ssion.com>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, linux-arch@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>, Netdev <netdev@...r.kernel.org>, Greg KH <gregkh@...uxfoundation.org>, Thomas Gleixner <tglx@...utronix.de>, "David S. Miller" <davem@...emloft.net>, Elena Reshetova <elena.reshetova@...el.com>, Alan Cox <alan@...ux.intel.com> Subject: Re: [PATCH 16/18] net: mpls: prevent bounds-check bypass via speculative execution On Tue, Jan 09, 2018 at 04:48:24PM -0800, Dan Williams wrote: > > #define __nospec_array_ptr(base, idx, sz) \ > ({ \ > union { typeof(&base[0]) _ptr; unsigned long _bit; } __u; \ > unsigned long _i = (idx); \ > unsigned long _s = (sz); \ > unsigned long _v = (long)(_i | _s - 1 - _i) \ > >> BITS_PER_LONG - 1; \ > unsigned long _mask = _v * ~0UL; \ > OPTIMIZER_HIDE_VAR(_mask); \ > __u._ptr = &base[_i & _mask]; \ > __u._bit &= _mask; \ > __u._ptr; \ > }) _v * ~0UL doesn't seem right and non intuitive. What's wrong with: unsigned long _mask = ~(long)(_i | _s - 1 - _i) >> BITS_PER_LONG - 1; and why OPTIMIZER_HIDE_VAR ? Could you remove '&' ? since in doesn't work for: struct { int fd[4]; ... } *fdt; it cannot be used as array_acces(fdt->fd, ...); Could you please drop nospec_ prefix since it is misleading ? This macro doesn't prevent speculation. I think array_access() was the best name so far.
Powered by blists - more mailing lists