This is a note to let you know that I've just added the patch titled
tracing/probes: Fix MAX_TRACE_ARGS limit handling
to the 6.11-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-probes-fix-max_trace_args-limit-handling.patch
and it can be found in the queue-6.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ff6cb2537676cb3ff35de727ed1af05515a402a4
Author: Mikel Rychliski <mikel@xxxxxxxxxx>
Date: Mon Sep 30 16:26:54 2024 -0400
tracing/probes: Fix MAX_TRACE_ARGS limit handling
[ Upstream commit 73f35080477e893aa6f4c8d388352b871b288fbc ]
When creating a trace_probe we would set nr_args prior to truncating the
arguments to MAX_TRACE_ARGS. However, we would only initialize arguments
up to the limit.
This caused invalid memory access when attempting to set up probes with
more than 128 fetchargs.
BUG: kernel NULL pointer dereference, address: 0000000000000020
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 0 UID: 0 PID: 1769 Comm: cat Not tainted 6.11.0-rc7+ #8
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-1.fc39 04/01/2014
RIP: 0010:__set_print_fmt+0x134/0x330
Resolve the issue by applying the MAX_TRACE_ARGS limit earlier. Return
an error when there are too many arguments instead of silently
truncating.
Link: https://lore.kernel.org/all/20240930202656.292869-1-mikel@xxxxxxxxxx/
Fixes: 035ba76014c0 ("tracing/probes: cleanup: Set trace_probe::nr_args at trace_probe_init")
Signed-off-by: Mikel Rychliski <mikel@xxxxxxxxxx>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
index b0e0ec85912e9..ebda68ee9abff 100644
--- a/kernel/trace/trace_eprobe.c
+++ b/kernel/trace/trace_eprobe.c
@@ -912,6 +912,11 @@ static int __trace_eprobe_create(int argc, const char *argv[])
}
}
+ if (argc - 2 > MAX_TRACE_ARGS) {
+ ret = -E2BIG;
+ goto error;
+ }
+
mutex_lock(&event_mutex);
event_call = find_and_get_event(sys_name, sys_event);
ep = alloc_event_probe(group, event, event_call, argc - 2);
@@ -937,7 +942,7 @@ static int __trace_eprobe_create(int argc, const char *argv[])
argc -= 2; argv += 2;
/* parse arguments */
- for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
+ for (i = 0; i < argc; i++) {
trace_probe_log_set_index(i + 2);
ret = trace_eprobe_tp_update_arg(ep, argv, i);
if (ret)
diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
index 62e6a8f4aae9b..5107d466a1293 100644
--- a/kernel/trace/trace_fprobe.c
+++ b/kernel/trace/trace_fprobe.c
@@ -1104,6 +1104,10 @@ static int __trace_fprobe_create(int argc, const char *argv[])
argc = new_argc;
argv = new_argv;
}
+ if (argc > MAX_TRACE_ARGS) {
+ ret = -E2BIG;
+ goto out;
+ }
ret = traceprobe_expand_dentry_args(argc, argv, &dbuf);
if (ret)
@@ -1124,7 +1128,7 @@ static int __trace_fprobe_create(int argc, const char *argv[])
(unsigned long)tf->tpoint->probestub);
/* parse arguments */
- for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
+ for (i = 0; i < argc; i++) {
trace_probe_log_set_index(i + 2);
ctx.offset = 0;
ret = traceprobe_parse_probe_arg(&tf->tp, i, argv[i], &ctx);
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 61a6da808203e..263fac44d3ca3 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1013,6 +1013,10 @@ static int __trace_kprobe_create(int argc, const char *argv[])
argc = new_argc;
argv = new_argv;
}
+ if (argc > MAX_TRACE_ARGS) {
+ ret = -E2BIG;
+ goto out;
+ }
ret = traceprobe_expand_dentry_args(argc, argv, &dbuf);
if (ret)
@@ -1029,7 +1033,7 @@ static int __trace_kprobe_create(int argc, const char *argv[])
}
/* parse arguments */
- for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
+ for (i = 0; i < argc; i++) {
trace_probe_log_set_index(i + 2);
ctx.offset = 0;
ret = traceprobe_parse_probe_arg(&tk->tp, i, argv[i], &ctx);
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 2c30d948e733c..6de07df05ed8c 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -556,6 +556,8 @@ static int __trace_uprobe_create(int argc, const char **argv)
if (argc < 2)
return -ECANCELED;
+ if (argc - 2 > MAX_TRACE_ARGS)
+ return -E2BIG;
if (argv[0][1] == ':')
event = &argv[0][2];
@@ -681,7 +683,7 @@ static int __trace_uprobe_create(int argc, const char **argv)
tu->filename = filename;
/* parse arguments */
- for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
+ for (i = 0; i < argc; i++) {
struct traceprobe_parse_context ctx = {
.flags = (is_return ? TPARG_FL_RETURN : 0) | TPARG_FL_USER,
};
