This is a note to let you know that I've just added the patch titled
tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tracing-kprobes-return-eaddrnotavail-when-func-matches-several-symbols.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b022f0c7e404887a7c5229788fc99eff9f9a80d5 Mon Sep 17 00:00:00 2001
From: Francis Laniel <flaniel@xxxxxxxxxxxxxxxxxxx>
Date: Fri, 20 Oct 2023 13:42:49 +0300
Subject: tracing/kprobes: Return EADDRNOTAVAIL when func matches several symbols
From: Francis Laniel <flaniel@xxxxxxxxxxxxxxxxxxx>
commit b022f0c7e404887a7c5229788fc99eff9f9a80d5 upstream.
When a kprobe is attached to a function that's name is not unique (is
static and shares the name with other functions in the kernel), the
kprobe is attached to the first function it finds. This is a bug as the
function that it is attaching to is not necessarily the one that the
user wants to attach to.
Instead of blindly picking a function to attach to what is ambiguous,
error with EADDRNOTAVAIL to let the user know that this function is not
unique, and that the user must use another unique function with an
address offset to get to the function they want to attach to.
Link: https://lore.kernel.org/all/20231020104250.9537-2-flaniel@xxxxxxxxxxxxxxxxxxx/
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 413d37d1eb69 ("tracing: Add kprobe-based event tracer")
Suggested-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Signed-off-by: Francis Laniel <flaniel@xxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/lkml/20230819101105.b0c104ae4494a7d1f2eea742@xxxxxxxxxx/
Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/trace/trace_kprobe.c | 48 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 48 insertions(+)
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -715,6 +715,36 @@ static inline void sanitize_event_name(c
*name = '_';
}
+struct count_symbols_struct {
+ const char *func_name;
+ unsigned int count;
+};
+
+static int count_symbols(void *data, const char *name, struct module *unused0,
+ unsigned long unused1)
+{
+ struct count_symbols_struct *args = data;
+
+ if (strcmp(args->func_name, name))
+ return 0;
+
+ args->count++;
+
+ return 0;
+}
+
+static unsigned int number_of_same_symbols(char *func_name)
+{
+ struct count_symbols_struct args = {
+ .func_name = func_name,
+ .count = 0,
+ };
+
+ kallsyms_on_each_symbol(count_symbols, &args);
+
+ return args.count;
+}
+
static int create_trace_kprobe(int argc, char **argv)
{
/*
@@ -845,6 +875,24 @@ static int create_trace_kprobe(int argc,
}
argc -= 2; argv += 2;
+ if (symbol && !strchr(symbol, ':')) {
+ unsigned int count;
+
+ count = number_of_same_symbols(symbol);
+ if (count > 1)
+ /*
+ * Users should use ADDR to remove the ambiguity of
+ * using KSYM only.
+ */
+ return -EADDRNOTAVAIL;
+ else if (count == 0)
+ /*
+ * We can return ENOENT earlier than when register the
+ * kprobe.
+ */
+ return -ENOENT;
+ }
+
/* setup a probe */
if (!event) {
/* Make a new event name */
Patches currently in stable-queue which might be from flaniel@xxxxxxxxxxxxxxxxxxx are
queue-4.19/tracing-kprobes-return-eaddrnotavail-when-func-matches-several-symbols.patch
