[PATCH v8 4/6] Uprobes/sdt: Prevent multiple reference counter for same uprobe

Ravi Bangoria
2018-08-09T04:19:33Z

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 <ravi.bangoria@linux.ibm.com>
---
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