From: Huihui Huang <[email protected]>
String event fields are not necessarily NUL-terminated, so the filter
predicate functions (filter_pred_string(), filter_pred_strloc() and
filter_pred_strrelloc()) pass the field length to the regex match
callbacks, and the length-aware matchers honour it.
regex_match_glob() was the exception: it ignored the length and called
glob_match(), which scans the string until it hits a NUL byte. Some
string fields are not NUL-terminated. One example is the dynamic char
array of the xfs_* namespace tracepoints, which is copied without a
trailing NUL. For such a field, glob matching reads past the end of
the event field, causing a KASAN slab-out-of-bounds read in
glob_match(), reached via regex_match_glob() and filter_match_preds()
from the xfs_lookup tracepoint.
Add a length-bounded glob_match_len() and use it from regex_match_glob()
so glob matching always stops at the field boundary. The matching loop
is factored into a shared helper so glob_match() keeps its behaviour.
Fixes: 60f1d5e3bac4 ("ftrace: Support full glob matching")
Cc: [email protected]
Reported-by: Yuan Tan <[email protected]>
Reported-by: Yifan Wu <[email protected]>
Reported-by: Juefei Pu <[email protected]>
Reported-by: Zhengchuan Liang <[email protected]>
Reported-by: Xin Liu <[email protected]>
Assisted-by: Codex:GPT-5.4
Signed-off-by: Huihui Huang <[email protected]>
Signed-off-by: Ren Wei <[email protected]>
---
include/linux/glob.h | 1 +
kernel/trace/trace_events_filter.c | 6 ++----
lib/glob.c | 31 ++++++++++++++++++++++++++++--
3 files changed, 32 insertions(+), 6 deletions(-)
diff --git a/include/linux/glob.h b/include/linux/glob.h
index 861327b33e..91595e7509 100644
--- a/include/linux/glob.h
+++ b/include/linux/glob.h
@@ -6,5 +6,6 @@
#include <linux/compiler.h> /* For __pure */
bool __pure glob_match(char const *pat, char const *str);
+bool __pure glob_match_len(char const *pat, char const *str, size_t len);
#endif /* _LINUX_GLOB_H */
diff --git a/kernel/trace/trace_events_filter.c
b/kernel/trace/trace_events_filter.c
index 609325f579..6385cd662d 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1056,11 +1056,9 @@ static int regex_match_end(char *str, struct regex *r,
int len)
return 0;
}
-static int regex_match_glob(char *str, struct regex *r, int len __maybe_unused)
+static int regex_match_glob(char *str, struct regex *r, int len)
{
- if (glob_match(r->pattern, str))
- return 1;
- return 0;
+ return glob_match_len(r->pattern, str, len) ? 1 : 0;
}
/**
diff --git a/lib/glob.c b/lib/glob.c
index 7aca76c25b..c80d9dd736 100644
--- a/lib/glob.c
+++ b/lib/glob.c
@@ -11,6 +11,9 @@
MODULE_DESCRIPTION("glob(7) matching");
MODULE_LICENSE("Dual MIT/GPL");
+static bool __pure glob_match_str(char const *pat, char const *str,
+ char const *str_end);
+
/**
* glob_match - Shell-style pattern matching, like !fnmatch(pat, str, 0)
* @pat: Shell-style pattern to match, e.g. "*.[ch]".
@@ -40,6 +43,29 @@ MODULE_LICENSE("Dual MIT/GPL");
* An opening bracket without a matching close is matched literally.
*/
bool __pure glob_match(char const *pat, char const *str)
+{
+ return glob_match_str(pat, str, NULL);
+}
+EXPORT_SYMBOL(glob_match);
+
+/**
+ * glob_match_len - glob match against a length-bounded string
+ * @pat: Shell-style pattern to match.
+ * @str: String to match. Need not be NUL-terminated.
+ * @len: Number of bytes of @str that may be read.
+ *
+ * Like glob_match(), but @str is only read up to @len bytes, so it can be
+ * used on buffers that are not NUL-terminated (e.g. trace event fields).
+ * A NUL byte within @len still terminates the string.
+ */
+bool __pure glob_match_len(char const *pat, char const *str, size_t len)
+{
+ return glob_match_str(pat, str, str + len);
+}
+EXPORT_SYMBOL(glob_match_len);
+
+static bool __pure glob_match_str(char const *pat, char const *str,
+ char const *str_end)
{
/*
* Backtrack to previous * on mismatch and retry starting one
@@ -55,9 +81,11 @@ bool __pure glob_match(char const *pat, char const *str)
* on mismatch, or true after matching the trailing nul bytes.
*/
for (;;) {
- unsigned char c = *str++;
+ unsigned char c = (str_end && str >= str_end) ? '\0' : *str;
unsigned char d = *pat++;
+ str++;
+
switch (d) {
case '?': /* Wildcard: anything but nul */
if (c == '\0')
@@ -125,4 +153,3 @@ bool __pure glob_match(char const *pat, char const *str)
}
}
}
-EXPORT_SYMBOL(glob_match);
--
2.50.1
