1 files changed, 55 insertions, 2 deletions

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 0914435001f5..0460d04f0acc 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -466,9 +466,58 @@ static bool branch_is_call(struct arch_uprobe *auprobe)
         return auprobe->branch.opc1 == 0xe8;
 }
 
+#define CASE_COND                                       \
+        COND(70, 71, XF(OF))                            \
+        COND(72, 73, XF(CF))                            \
+        COND(74, 75, XF(ZF))                            \
+        COND(78, 79, XF(SF))                            \
+        COND(7a, 7b, XF(PF))                            \
+        COND(76, 77, XF(CF) || XF(ZF))                  \
+        COND(7c, 7d, XF(SF) != XF(OF))                  \
+        COND(7e, 7f, XF(ZF) || XF(SF) != XF(OF))
+
+#define COND(op_y, op_n, expr)                          \
+        case 0x ## op_y: DO((expr) != 0)                \
+        case 0x ## op_n: DO((expr) == 0)
+
+#define XF(xf)  (!!(flags & X86_EFLAGS_ ## xf))
+
+static bool is_cond_jmp_opcode(u8 opcode)
+{
+        switch (opcode) {
+        #define DO(expr)        \
+                return true;
+        CASE_COND
+        #undef  DO
+
+        default:
+                return false;
+        }
+}
+
+static bool check_jmp_cond(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+        unsigned long flags = regs->flags;
+
+        switch (auprobe->branch.opc1) {
+        #define DO(expr)        \
+                return expr;
+        CASE_COND
+        #undef  DO
+
+        default:        /* not a conditional jmp */
+                return true;
+        }
+}
+
+#undef  XF
+#undef  COND
+#undef  CASE_COND
+
 static bool branch_emulate_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
 {
         unsigned long new_ip = regs->ip += auprobe->branch.ilen;
+        unsigned long offs = (long)auprobe->branch.offs;
 
         if (branch_is_call(auprobe)) {
                 unsigned long new_sp = regs->sp - sizeof_long();
@@ -484,9 +533,11 @@ static bool branch_emulate_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
                 if (copy_to_user((void __user *)new_sp, &new_ip, sizeof_long()))
                         return false;
                 regs->sp = new_sp;
+        } else if (!check_jmp_cond(auprobe, regs)) {
+                offs = 0;
         }
 
-        regs->ip = new_ip + auprobe->branch.offs;
+        regs->ip = new_ip + offs;
         return true;
 }
 
@@ -547,8 +598,10 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
         case 0xe8:      /* call relative */
                 branch_clear_offset(auprobe, insn);
                 break;
+
         default:
-                return -ENOSYS;
+                if (!is_cond_jmp_opcode(opc1))
+                        return -ENOSYS;
         }
 
         auprobe->branch.opc1 = opc1;