diff options
Diffstat (limited to 'main/xen/xsa193-4.7.patch')
| -rw-r--r-- | main/xen/xsa193-4.7.patch | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/main/xen/xsa193-4.7.patch b/main/xen/xsa193-4.7.patch new file mode 100644 index 0000000000..c5486efa54 --- /dev/null +++ b/main/xen/xsa193-4.7.patch @@ -0,0 +1,68 @@ +From: Jan Beulich <jbeulich@suse.com> +Subject: x86/PV: writes of %fs and %gs base MSRs require canonical addresses + +Commit c42494acb2 ("x86: fix FS/GS base handling when using the +fsgsbase feature") replaced the use of wrmsr_safe() on these paths +without recognizing that wr{f,g}sbase() use just wrmsrl() and that the +WR{F,G}SBASE instructions also raise #GP for non-canonical input. + +Similarly arch_set_info_guest() needs to prevent non-canonical +addresses from getting stored into state later to be loaded by context +switch code. For consistency also check stack pointers and LDT base. +DR0..3, otoh, already get properly checked in set_debugreg() (albeit +we discard the error there). + +The SHADOW_GS_BASE check isn't strictly necessary, but I think we +better avoid trying the WRMSR if we know it's going to fail. + +This is XSA-193. + +Reported-by: Andrew Cooper <andrew.cooper3@citrix.com> +Signed-off-by: Jan Beulich <jbeulich@suse.com> +Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com> + +--- a/xen/arch/x86/domain.c ++++ b/xen/arch/x86/domain.c +@@ -890,7 +890,13 @@ int arch_set_info_guest( + { + if ( !compat ) + { +- if ( !is_canonical_address(c.nat->user_regs.eip) || ++ if ( !is_canonical_address(c.nat->user_regs.rip) || ++ !is_canonical_address(c.nat->user_regs.rsp) || ++ !is_canonical_address(c.nat->kernel_sp) || ++ (c.nat->ldt_ents && !is_canonical_address(c.nat->ldt_base)) || ++ !is_canonical_address(c.nat->fs_base) || ++ !is_canonical_address(c.nat->gs_base_kernel) || ++ !is_canonical_address(c.nat->gs_base_user) || + !is_canonical_address(c.nat->event_callback_eip) || + !is_canonical_address(c.nat->syscall_callback_eip) || + !is_canonical_address(c.nat->failsafe_callback_eip) ) +--- a/xen/arch/x86/traps.c ++++ b/xen/arch/x86/traps.c +@@ -2723,19 +2723,22 @@ static int emulate_privileged_op(struct + switch ( regs->_ecx ) + { + case MSR_FS_BASE: +- if ( is_pv_32bit_domain(currd) ) ++ if ( is_pv_32bit_domain(currd) || ++ !is_canonical_address(msr_content) ) + goto fail; + wrfsbase(msr_content); + v->arch.pv_vcpu.fs_base = msr_content; + break; + case MSR_GS_BASE: +- if ( is_pv_32bit_domain(currd) ) ++ if ( is_pv_32bit_domain(currd) || ++ !is_canonical_address(msr_content) ) + goto fail; + wrgsbase(msr_content); + v->arch.pv_vcpu.gs_base_kernel = msr_content; + break; + case MSR_SHADOW_GS_BASE: +- if ( is_pv_32bit_domain(currd) ) ++ if ( is_pv_32bit_domain(currd) || ++ !is_canonical_address(msr_content) ) + goto fail; + if ( wrmsr_safe(MSR_SHADOW_GS_BASE, msr_content) ) + goto fail; |