Date: Fri, 22 Jul 2016 00:43:12 -0400 From: Valdis.Kletnieks@...edu To: kernel-hardening@...ts.openwall.com Cc: x86@...nel.org, linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org, Borislav Petkov <bp@...en8.de>, Nadav Amit <nadav.amit@...il.com>, Kees Cook <keescook@...omium.org>, Brian Gerst <brgerst@...il.com>, Linus Torvalds <torvalds@...ux-foundation.org>, Josh Poimboeuf <jpoimboe@...hat.com>, Jann Horn <jann@...jh.net>, Heiko Carstens <heiko.carstens@...ibm.com>, Andy Lutomirski <luto@...nel.org> Subject: Re: [PATCH v5 03/32] x86/cpa: In populate_pgd, don't set the pgd entry until it's populated On Mon, 11 Jul 2016 13:53:36 -0700, Andy Lutomirski said: > This avoids pointless races in which another CPU or task might see a > partially populated global pgd entry. These races should normally > be harmless, but, if another CPU propagates the entry via > vmalloc_fault and then populate_pgd fails (due to memory allocation > failure, for example), this prevents a use-after-free of the pgd > entry. > > Signed-off-by: Andy Lutomirski <luto@...nel.org> > --- > arch/x86/mm/pageattr.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) I just bisected a failure to boot down to this patch. On my Dell Latitude laptop, it results in the kernel being loaded and then just basically sitting there dead in the water - as far as I can tell, it dies before the kernel ever gets going far enough to do any console I/O (even with ignore_loglevel). Nothing in /sys/fs/pstore either. I admit not understanding the VM code at all, so I don't have a clue *why* this causes indigestion... CPU is an Intel Core i5-3340M in case that matters.... Content of type "application/pgp-signature" skipped
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