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tracing/probes: Fix MAX_TRACE_ARGS limit handling
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@mikelr.com/
Fixes: 035ba76014
("tracing/probes: cleanup: Set trace_probe::nr_args at trace_probe_init")
Signed-off-by: Mikel Rychliski <mikel@mikelr.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
This commit is contained in:
parent
aff1871bfc
commit
73f3508047
@ -912,6 +912,11 @@ static int __trace_eprobe_create(int argc, const char *argv[])
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}
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}
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if (argc - 2 > MAX_TRACE_ARGS) {
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ret = -E2BIG;
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goto error;
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}
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mutex_lock(&event_mutex);
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event_call = find_and_get_event(sys_name, sys_event);
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ep = alloc_event_probe(group, event, event_call, argc - 2);
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@ -937,7 +942,7 @@ static int __trace_eprobe_create(int argc, const char *argv[])
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argc -= 2; argv += 2;
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/* parse arguments */
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for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
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for (i = 0; i < argc; i++) {
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trace_probe_log_set_index(i + 2);
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ret = trace_eprobe_tp_update_arg(ep, argv, i);
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if (ret)
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@ -1187,6 +1187,10 @@ static int __trace_fprobe_create(int argc, const char *argv[])
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argc = new_argc;
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argv = new_argv;
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}
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if (argc > MAX_TRACE_ARGS) {
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ret = -E2BIG;
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goto out;
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}
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ret = traceprobe_expand_dentry_args(argc, argv, &dbuf);
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if (ret)
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@ -1203,7 +1207,7 @@ static int __trace_fprobe_create(int argc, const char *argv[])
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}
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/* parse arguments */
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for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
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for (i = 0; i < argc; i++) {
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trace_probe_log_set_index(i + 2);
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ctx.offset = 0;
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ret = traceprobe_parse_probe_arg(&tf->tp, i, argv[i], &ctx);
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@ -1013,6 +1013,10 @@ static int __trace_kprobe_create(int argc, const char *argv[])
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argc = new_argc;
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argv = new_argv;
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}
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if (argc > MAX_TRACE_ARGS) {
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ret = -E2BIG;
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goto out;
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}
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ret = traceprobe_expand_dentry_args(argc, argv, &dbuf);
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if (ret)
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@ -1029,7 +1033,7 @@ static int __trace_kprobe_create(int argc, const char *argv[])
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}
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/* parse arguments */
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for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
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for (i = 0; i < argc; i++) {
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trace_probe_log_set_index(i + 2);
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ctx.offset = 0;
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ret = traceprobe_parse_probe_arg(&tk->tp, i, argv[i], &ctx);
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@ -565,6 +565,8 @@ static int __trace_uprobe_create(int argc, const char **argv)
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if (argc < 2)
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return -ECANCELED;
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if (argc - 2 > MAX_TRACE_ARGS)
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return -E2BIG;
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if (argv[0][1] == ':')
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event = &argv[0][2];
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@ -690,7 +692,7 @@ static int __trace_uprobe_create(int argc, const char **argv)
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tu->filename = filename;
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/* parse arguments */
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for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
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for (i = 0; i < argc; i++) {
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struct traceprobe_parse_context ctx = {
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.flags = (is_return ? TPARG_FL_RETURN : 0) | TPARG_FL_USER,
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};
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