[PATCH 1/1] tracing: Prevent out-of-bounds read in glob matching
From: Ren Wei <hidden>
Date: 2026-07-01 10:29:24
Also in:
lkml
Subsystem:
library code, the rest, tracing · Maintainers:
Andrew Morton, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
From: Huihui Huang <redacted>
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: stable@vger.kernel.org
Reported-by: Yuan Tan <redacted>
Reported-by: Yifan Wu <redacted>
Reported-by: Juefei Pu <redacted>
Reported-by: Zhengchuan Liang <redacted>
Reported-by: Xin Liu <redacted>
Assisted-by: Codex:GPT-5.4
Signed-off-by: Huihui Huang <redacted>
Signed-off-by: Ren Wei <redacted>
---
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