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authorRavi Bangoria <ravi.bangoria@linux.ibm.com>2018-08-20 06:42:49 +0200
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2018-09-24 10:44:54 +0200
commitccea8727dc27d8f46df6557f9260ab32760ef409 (patch)
tree2c414868068fa1928f52fd5d295f3e17a5ff1c42 /kernel/trace
parentuprobes/sdt: Prevent multiple reference counter for same uprobe (diff)
downloadlinux-ccea8727dc27d8f46df6557f9260ab32760ef409.tar.xz
linux-ccea8727dc27d8f46df6557f9260ab32760ef409.zip
trace_uprobe/sdt: Prevent multiple reference counter for same uprobe
We assume to have only one reference counter for one uprobe. Don't allow user to add multiple trace_uprobe entries having same inode+offset but different reference counter. Ex, # echo "p:sdt_tick/loop2 /home/ravi/tick:0x6e4(0x10036)" > uprobe_events # echo "p:sdt_tick/loop2_1 /home/ravi/tick:0x6e4(0xfffff)" >> uprobe_events bash: echo: write error: Invalid argument # dmesg trace_kprobe: Reference counter offset mismatch. There is one exception though: When user is trying to replace the old entry with the new one, we allow this if the new entry does not conflict with any other existing entries. Link: http://lkml.kernel.org/r/20180820044250.11659-4-ravi.bangoria@linux.ibm.com Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Reviewed-by: Song Liu <songliubraving@fb.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Tested-by: Song Liu <songliubraving@fb.com> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/trace_uprobe.c37
1 files changed, 35 insertions, 2 deletions
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 7b85172beab6..3a7c73c40007 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -312,6 +312,35 @@ static int unregister_trace_uprobe(struct trace_uprobe *tu)
return 0;
}
+/*
+ * Uprobe with multiple reference counter is not allowed. i.e.
+ * If inode and offset matches, reference counter offset *must*
+ * match as well. Though, there is one exception: If user is
+ * replacing old trace_uprobe with new one(same group/event),
+ * then we allow same uprobe with new reference counter as far
+ * as the new one does not conflict with any other existing
+ * ones.
+ */
+static struct trace_uprobe *find_old_trace_uprobe(struct trace_uprobe *new)
+{
+ struct trace_uprobe *tmp, *old = NULL;
+ struct inode *new_inode = d_real_inode(new->path.dentry);
+
+ old = find_probe_event(trace_event_name(&new->tp.call),
+ new->tp.call.class->system);
+
+ list_for_each_entry(tmp, &uprobe_list, list) {
+ if ((old ? old != tmp : true) &&
+ new_inode == d_real_inode(tmp->path.dentry) &&
+ new->offset == tmp->offset &&
+ new->ref_ctr_offset != tmp->ref_ctr_offset) {
+ pr_warn("Reference counter offset mismatch.");
+ return ERR_PTR(-EINVAL);
+ }
+ }
+ return old;
+}
+
/* Register a trace_uprobe and probe_event */
static int register_trace_uprobe(struct trace_uprobe *tu)
{
@@ -321,8 +350,12 @@ static int register_trace_uprobe(struct trace_uprobe *tu)
mutex_lock(&uprobe_lock);
/* register as an event */
- old_tu = find_probe_event(trace_event_name(&tu->tp.call),
- tu->tp.call.class->system);
+ old_tu = find_old_trace_uprobe(tu);
+ if (IS_ERR(old_tu)) {
+ ret = PTR_ERR(old_tu);
+ goto end;
+ }
+
if (old_tu) {
/* delete old event */
ret = unregister_trace_uprobe(old_tu);