diff mbox series

[SRU,F,1/3] ftrace: Separate out functionality from ftrace_location_range()

Message ID 20241025133110.2839066-2-koichiro.den@canonical.com
State New
Headers show
Series CVE-2024-38588 | expand

Commit Message

Koichiro Den Oct. 25, 2024, 1:31 p.m. UTC 
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

Create a new function called lookup_rec() from the functionality of
ftrace_location_range(). The difference between lookup_rec() is that it
returns the record that it finds, where as ftrace_location_range() returns
only if it found a match or not.

The lookup_rec() is static, and can be used for new functionality where
ftrace needs to find a record of a specific address.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
(backported from commit 7e16f581a81759bafea04d049134b32d1a881226)
[koichiroden: Prerequisite for "ftrace: Fix possible use-after-free
issue in ftrace_location()". Adjusted context due to an extra commit
170d0fe552d0 in this tree, backported from v5.4.238 ac58b88ccbbb
("ftrace: Fix invalid address access in lookup_rec() when index is 0")]
CVE-2024-38588
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
---
 kernel/trace/ftrace.c | 40 ++++++++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 16 deletions(-)
diff mbox series

Patch

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 412505d94865..d9992fef7287 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1535,22 +1535,10 @@  static int ftrace_cmp_recs(const void *a, const void *b)
 	return 0;
 }
 
-/**
- * ftrace_location_range - return the first address of a traced location
- *	if it touches the given ip range
- * @start: start of range to search.
- * @end: end of range to search (inclusive). @end points to the last byte
- *	to check.
- *
- * Returns rec->ip if the related ftrace location is a least partly within
- * the given address range. That is, the first address of the instruction
- * that is either a NOP or call to the function tracer. It checks the ftrace
- * internal tables to determine if the address belongs or not.
- */
-unsigned long ftrace_location_range(unsigned long start, unsigned long end)
+static struct dyn_ftrace *lookup_rec(unsigned long start, unsigned long end)
 {
 	struct ftrace_page *pg;
-	struct dyn_ftrace *rec;
+	struct dyn_ftrace *rec = NULL;
 	struct dyn_ftrace key;
 
 	key.ip = start;
@@ -1564,9 +1552,29 @@  unsigned long ftrace_location_range(unsigned long start, unsigned long end)
 		rec = bsearch(&key, pg->records, pg->index,
 			      sizeof(struct dyn_ftrace),
 			      ftrace_cmp_recs);
-		if (rec)
-			return rec->ip;
 	}
+	return rec;
+}
+
+/**
+ * ftrace_location_range - return the first address of a traced location
+ *	if it touches the given ip range
+ * @start: start of range to search.
+ * @end: end of range to search (inclusive). @end points to the last byte
+ *	to check.
+ *
+ * Returns rec->ip if the related ftrace location is a least partly within
+ * the given address range. That is, the first address of the instruction
+ * that is either a NOP or call to the function tracer. It checks the ftrace
+ * internal tables to determine if the address belongs or not.
+ */
+unsigned long ftrace_location_range(unsigned long start, unsigned long end)
+{
+	struct dyn_ftrace *rec;
+
+	rec = lookup_rec(start, end);
+	if (rec)
+		return rec->ip;
 
 	return 0;
 }