From: Juergen Gross jgross@suse.com
stable inclusion from stable-v6.6.67 commit 82c211ead1ec440dbf81727e17b03b5e3c44b93d category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBCAZE CVE: CVE-2024-53241
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit a2796dff62d6c6bfc5fbebdf2bee0d5ac0438906 upstream.
Instead of jumping to the Xen hypercall page for doing the iret hypercall, directly code the required sequence in xen-asm.S.
This is done in preparation of no longer using hypercall page at all, as it has shown to cause problems with speculation mitigations.
This is part of XSA-466 / CVE-2024-53241.
Reported-by: Andrew Cooper andrew.cooper3@citrix.com Signed-off-by: Juergen Gross jgross@suse.com Reviewed-by: Jan Beulich jbeulich@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Heyuan Wang wangheyuan2@h-partners.com --- arch/x86/xen/xen-asm.S | 27 ++++++++++++++++++--------- 1 file changed, 18 insertions(+), 9 deletions(-)
diff --git a/arch/x86/xen/xen-asm.S b/arch/x86/xen/xen-asm.S index 1a9cd18dfbd3..72f61a69f72e 100644 --- a/arch/x86/xen/xen-asm.S +++ b/arch/x86/xen/xen-asm.S @@ -176,7 +176,6 @@ SYM_CODE_START(xen_early_idt_handler_array) SYM_CODE_END(xen_early_idt_handler_array) __FINIT
-hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32 /* * Xen64 iret frame: * @@ -186,17 +185,28 @@ hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32 * cs * rip <-- standard iret frame * - * flags + * flags <-- xen_iret must push from here on * - * rcx } - * r11 }<-- pushed by hypercall page - * rsp->rax } + * rcx + * r11 + * rsp->rax */ +.macro xen_hypercall_iret + pushq $0 /* Flags */ + push %rcx + push %r11 + push %rax + mov $__HYPERVISOR_iret, %eax + syscall /* Do the IRET. */ +#ifdef CONFIG_MITIGATION_SLS + int3 +#endif +.endm + SYM_CODE_START(xen_iret) UNWIND_HINT_UNDEFINED ANNOTATE_NOENDBR - pushq $0 - jmp hypercall_iret + xen_hypercall_iret SYM_CODE_END(xen_iret)
/* @@ -301,8 +311,7 @@ SYM_CODE_START(xen_entry_SYSENTER_compat) ENDBR lea 16(%rsp), %rsp /* strip %rcx, %r11 */ mov $-ENOSYS, %rax - pushq $0 - jmp hypercall_iret + xen_hypercall_iret SYM_CODE_END(xen_entry_SYSENTER_compat) SYM_CODE_END(xen_entry_SYSCALL_compat)