diff options
Diffstat (limited to 'system/xen/xsa/xsa200-4.7.patch')
-rw-r--r-- | system/xen/xsa/xsa200-4.7.patch | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/system/xen/xsa/xsa200-4.7.patch b/system/xen/xsa/xsa200-4.7.patch new file mode 100644 index 0000000000000..69608f6fc3187 --- /dev/null +++ b/system/xen/xsa/xsa200-4.7.patch @@ -0,0 +1,55 @@ +From: Jan Beulich <jbeulich@suse.com> +Subject: x86emul: CMPXCHG8B ignores operand size prefix + +Otherwise besides mis-handling the instruction, the comparison failure +case would result in uninitialized stack data being handed back to the +guest in rDX:rAX (32 bits leaked for 32-bit guests, 96 bits for 64-bit +ones). + +This is XSA-200. + +Signed-off-by: Jan Beulich <jbeulich@suse.com> + +--- a/tools/tests/x86_emulator/test_x86_emulator.c ++++ b/tools/tests/x86_emulator/test_x86_emulator.c +@@ -435,6 +435,24 @@ int main(int argc, char **argv) + goto fail; + printf("okay\n"); + ++ printf("%-40s", "Testing cmpxchg8b (%edi) [opsize]..."); ++ instr[0] = 0x66; instr[1] = 0x0f; instr[2] = 0xc7; instr[3] = 0x0f; ++ res[0] = 0x12345678; ++ res[1] = 0x87654321; ++ regs.eflags = 0x200; ++ regs.eip = (unsigned long)&instr[0]; ++ regs.edi = (unsigned long)res; ++ rc = x86_emulate(&ctxt, &emulops); ++ if ( (rc != X86EMUL_OKAY) || ++ (res[0] != 0x12345678) || ++ (res[1] != 0x87654321) || ++ (regs.eax != 0x12345678) || ++ (regs.edx != 0x87654321) || ++ ((regs.eflags&0x240) != 0x200) || ++ (regs.eip != (unsigned long)&instr[4]) ) ++ goto fail; ++ printf("okay\n"); ++ + printf("%-40s", "Testing movsxbd (%%eax),%%ecx..."); + instr[0] = 0x0f; instr[1] = 0xbe; instr[2] = 0x08; + regs.eflags = 0x200; +--- a/xen/arch/x86/x86_emulate/x86_emulate.c ++++ b/xen/arch/x86/x86_emulate/x86_emulate.c +@@ -4775,8 +4775,12 @@ x86_emulate( + generate_exception_if((modrm_reg & 7) != 1, EXC_UD, -1); + generate_exception_if(ea.type != OP_MEM, EXC_UD, -1); + if ( op_bytes == 8 ) ++ { + host_and_vcpu_must_have(cx16); +- op_bytes *= 2; ++ op_bytes = 16; ++ } ++ else ++ op_bytes = 8; + + /* Get actual old value. */ + if ( (rc = ops->read(ea.mem.seg, ea.mem.off, old, op_bytes, |