Messages in this thread | | | Subject | Re: [PATCH 3.13 106/162] KVM: x86: Fix far-jump to non-canonical check | From | Kamal Mostafa <> | Date | Tue, 13 Jan 2015 10:38:58 -0800 |
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On Wed, 2014-12-31 at 00:27 +0200, Nadav Amit wrote: > Vinson Lee <vlee@twopensource.com> wrote: > > > On Thu, Nov 6, 2014 at 2:36 PM, Kamal Mostafa <kamal@canonical.com> wrote: > >> 3.13.11.11 -stable review patch. If anyone has any objections, please let me know. > >> > >> ------------------ > >> > >> From: Nadav Amit <namit@cs.technion.ac.il> > >> > >> commit 7e46dddd6f6cd5dbf3c7bd04a7e75d19475ac9f2 upstream. > >> > >> Commit d1442d85cc30 ("KVM: x86: Handle errors when RIP is set during far > >> jumps") introduced a bug that caused the fix to be incomplete. Due to > >> incorrect evaluation, far jump to segment with L bit cleared (i.e., 32-bit > >> segment) and RIP with any of the high bits set (i.e, RIP[63:32] != 0) set may > >> not trigger #GP. As we know, this imposes a security problem. > >> > >> In addition, the condition for two warnings was incorrect. > >> > >> Fixes: d1442d85cc30ea75f7d399474ca738e0bc96f715 > >> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> > >> Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> > >> [Add #ifdef CONFIG_X86_64 to avoid complaints of undefined behavior. - Paolo] > >> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > >> [ kamal: backport to 3.13-stable: omitted WARN_ON fixes (not in 3.13) ] > >> Signed-off-by: Kamal Mostafa <kamal@canonical.com> > >> --- > >> arch/x86/kvm/emulate.c | 4 +++- > >> 1 file changed, 3 insertions(+), 1 deletion(-) > >> > >> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c > >> index a440bea..4ae37e7 100644 > >> --- a/arch/x86/kvm/emulate.c > >> +++ b/arch/x86/kvm/emulate.c > >> @@ -581,12 +581,14 @@ static inline int assign_eip_far(struct x86_emulate_ctxt *ctxt, ulong dst, > >> case 4: > >> ctxt->_eip = (u32)dst; > >> break; > >> +#ifdef CONFIG_X86_64 > >> case 8: > >> if ((cs_l && is_noncanonical_address(dst)) || > >> - (!cs_l && (dst & ~(u32)-1))) > >> + (!cs_l && (dst >> 32) != 0)) > >> return emulate_gp(ctxt, 0); > >> ctxt->_eip = dst; > >> break; > >> +#endif > >> default: > >> WARN(1, "unsupported eip assignment size\n"); > >> } > >> -- > >> 1.9.1 > >> > >> -- > >> To unsubscribe from this list: send the line "unsubscribe stable" in > >> the body of a message to majordomo@vger.kernel.org > >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > > Hi. > > > > Should the WARN_ON fixes have been included as well in 3.13.11.11?
Yes, they should have been. I wrongly omitted the WARN_ON fixes from the 3.13-stable backport due to some patch application order confusion. Thanks very much for catching this, Vinson!
> > WARN_ON hunks were added with the backport of "KVM: x86: Handle errors > > when RIP is set during far jumps" in 3.13.11.11 commit > > b8ba339d86fb627d54fea929492114d45f6835c2. > > If it was added, it should be fixed. The WARN_ON mistakenly has > double-negation. > > Nadav
I'll queue up the WARN_ON fixes for the next 3.13-stable.
Thanks again, Vinson and Nadav.
-Kamal
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