Messages in this thread Patch in this message | | | From | Ravi Bangoria <> | Subject | [PATCH 5/7] Uprobes/sdt: Prevent multiple reference counter for same uprobe | Date | Wed, 6 Jun 2018 14:03:42 +0530 |
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Even if we don't allow to create same uprobe with different reference counter offset via trace_uprobe, user can still create such uprobes by creating one uprobe using trace_uprobe and other by directly calling uprobe_register() from kernel module. Prevent such scenarios.
Note that, we are restricting user to not use both ways (trace_uprobe and kernel module) simultaneously. Ex, User can not trace single uprobe (with reference counter) simultaneously with Systemtap and perf at the same time.
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 279c8fc..5e07f99 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -526,6 +526,12 @@ 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("Err: Reference counter mismatch.\n"); + put_uprobe(cur_uprobe); + kfree(uprobe); + return ERR_PTR(-EINVAL); + } kfree(uprobe); uprobe = cur_uprobe; } @@ -1184,6 +1190,9 @@ 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. -- 1.8.3.1
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