kprobes/x86: Fix the return address of multiple kretprobes

[net-next-2.6.git] / arch / x86 / kernel / kprobes.c

diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index 1bfb6cf4dd55d67aeeebbbf89d0bb60283a94c94..770ebfb349e93efe3367cf0c6caff93b61b8b884 100644 (file)
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -709,6 +709,7 @@ static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
        struct hlist_node *node, *tmp;
        unsigned long flags, orig_ret_address = 0;
        unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
+       kprobe_opcode_t *correct_ret_addr = NULL;
 
        INIT_HLIST_HEAD(&empty_rp);
        kretprobe_hash_lock(current, &head, &flags);
@@ -740,14 +741,34 @@ static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
                        /* another task is sharing our hash bucket */
                        continue;
 
+               orig_ret_address = (unsigned long)ri->ret_addr;
+
+               if (orig_ret_address != trampoline_address)
+                       /*
+                        * This is the real return address. Any other
+                        * instances associated with this task are for
+                        * other calls deeper on the call stack
+                        */
+                       break;
+       }
+
+       kretprobe_assert(ri, orig_ret_address, trampoline_address);
+
+       correct_ret_addr = ri->ret_addr;
+       hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
+               if (ri->task != current)
+                       /* another task is sharing our hash bucket */
+                       continue;
+
+               orig_ret_address = (unsigned long)ri->ret_addr;
                if (ri->rp && ri->rp->handler) {
                        __get_cpu_var(current_kprobe) = &ri->rp->kp;
                        get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
+                       ri->ret_addr = correct_ret_addr;
                        ri->rp->handler(ri, regs);
                        __get_cpu_var(current_kprobe) = NULL;
                }
 
-               orig_ret_address = (unsigned long)ri->ret_addr;
                recycle_rp_inst(ri, &empty_rp);
 
                if (orig_ret_address != trampoline_address)
@@ -759,8 +780,6 @@ static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
                        break;
        }
 
-       kretprobe_assert(ri, orig_ret_address, trampoline_address);
-
        kretprobe_hash_unlock(current, &flags);
 
        hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {