We assume to have only one reference counter for one uprobe.
Don't allow user to register multiple uprobes having same
inode+offset but different reference counter.

Signed-off-by: Ravi Bangoria <redacted>
---
 kernel/events/uprobes.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 61b0481ef417..492a0e005b4d 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c

@@ -689,6 +689,12 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset,
        cur_uprobe = insert_uprobe(uprobe);
        /* a uprobe exists for this inode:offset combination */
        if (cur_uprobe) {
+               if (cur_uprobe->ref_ctr_offset != uprobe->ref_ctr_offset) {
+                       pr_warn("Reference counter offset mismatch.\n");

+                       put_uprobe(cur_uprobe);
+                       kfree(uprobe);
+                       return ERR_PTR(-EINVAL);
+               }
                kfree(uprobe);
                uprobe = cur_uprobe;
        }

@@ -1103,6 +1109,9 @@ static int __uprobe_register(struct inode *inode, loff_t offset,
        uprobe = alloc_uprobe(inode, offset, ref_ctr_offset);
        if (!uprobe)
                return -ENOMEM;
+       if (IS_ERR(uprobe))
+               return PTR_ERR(uprobe);
+
        /*
         * We can race with uprobe_unregister()->delete_uprobe().
         * Check uprobe_is_active() and retry if it is false.
--

2.14.4