6.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mikel Rychliski <mikel@xxxxxxxxxx> [ 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> --- kernel/trace/trace_eprobe.c | 7 ++++++- kernel/trace/trace_fprobe.c | 6 +++++- kernel/trace/trace_kprobe.c | 6 +++++- kernel/trace/trace_uprobe.c | 4 +++- 4 files changed, 19 insertions(+), 4 deletions(-) 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, }; -- 2.43.0
