62 lines
2.1 KiB
Diff
62 lines
2.1 KiB
Diff
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References: bsc#988676 CVE-2016-6259 XSA-183
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# Commit 9f1441487aa215193a7c00fd9cb80b335542465e
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# Date 2016-07-26 14:07:04 +0100
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# Author Andrew Cooper <andrew.cooper3@citrix.com>
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# Committer Andrew Cooper <andrew.cooper3@citrix.com>
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x86/entry: Avoid SMAP violation in compat_create_bounce_frame()
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A 32bit guest kernel might be running on user mappings.
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compat_create_bounce_frame() must whitelist its guest accesses to avoid
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risking a SMAP violation.
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For both variants of create_bounce_frame(), re-blacklist user accesses if
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execution exits via an exception table redirection.
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This is XSA-183 / CVE-2016-6259
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Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
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Reviewed-by: George Dunlap <george.dunlap@citrix.com>
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Reviewed-by: Jan Beulich <jbeulich@suse.com>
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--- a/xen/arch/x86/x86_64/compat/entry.S
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+++ b/xen/arch/x86/x86_64/compat/entry.S
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@@ -318,6 +318,7 @@ ENTRY(compat_int80_direct_trap)
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compat_create_bounce_frame:
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ASSERT_INTERRUPTS_ENABLED
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mov %fs,%edi
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+ ASM_STAC
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testb $2,UREGS_cs+8(%rsp)
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jz 1f
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/* Push new frame at registered guest-OS stack base. */
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@@ -364,6 +365,7 @@ compat_create_bounce_frame:
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movl TRAPBOUNCE_error_code(%rdx),%eax
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.Lft8: movl %eax,%fs:(%rsi) # ERROR CODE
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1:
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+ ASM_CLAC
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/* Rewrite our stack frame and return to guest-OS mode. */
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/* IA32 Ref. Vol. 3: TF, VM, RF and NT flags are cleared on trap. */
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andl $~(X86_EFLAGS_VM|X86_EFLAGS_RF|\
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@@ -403,6 +405,7 @@ compat_crash_page_fault_4:
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addl $4,%esi
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compat_crash_page_fault:
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.Lft14: mov %edi,%fs
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+ ASM_CLAC
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movl %esi,%edi
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call show_page_walk
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jmp dom_crash_sync_extable
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--- a/xen/arch/x86/x86_64/entry.S
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+++ b/xen/arch/x86/x86_64/entry.S
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@@ -420,9 +420,11 @@ domain_crash_page_fault_16:
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domain_crash_page_fault_8:
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addq $8,%rsi
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domain_crash_page_fault:
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+ ASM_CLAC
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movq %rsi,%rdi
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call show_page_walk
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ENTRY(dom_crash_sync_extable)
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+ ASM_CLAC
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# Get out of the guest-save area of the stack.
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GET_STACK_END(ax)
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leaq STACK_CPUINFO_FIELD(guest_cpu_user_regs)(%rax),%rsp
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