From 15f197856d68882af9416fc97516bb55079b7677 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Mon, 20 Jul 2026 19:12:10 +0900 Subject: [PATCH 1/4] tracing/probes: Avoid temporary buffer truncation in trace_probe_match_command_args() In trace_probe_match_command_args(), a stack buffer buf[MAX_ARGSTR_LEN + 1] (256 bytes) is used to format "=". However, since name can be up to 32 bytes (MAX_ARG_NAME_LEN) and comm up to 255 bytes (MAX_ARGSTR_LEN), the formatted string can exceed 256 bytes and get truncated by snprintf(), causing spurious argument matching failures. Instead of formatting into a temporary buffer on stack, compare the argument name, the '=' delimiter, and the comm expression directly. Link: https://lore.kernel.org/all/178454233010.290363.10428767141343428804.stgit@devnote2/ Fixes: eb5bf81330a7 ("tracing/kprobe: Add per-probe delete from event") Cc: stable@vger.kernel.org Assisted-by: Antigravity:gemini-3.5-flash Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_probe.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index d17cfee77d9c..95e3d072321f 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -2338,16 +2338,17 @@ int trace_probe_compare_arg_type(struct trace_probe *a, struct trace_probe *b) bool trace_probe_match_command_args(struct trace_probe *tp, int argc, const char **argv) { - char buf[MAX_ARGSTR_LEN + 1]; int i; if (tp->nr_args < argc) return false; for (i = 0; i < argc; i++) { - snprintf(buf, sizeof(buf), "%s=%s", - tp->args[i].name, tp->args[i].comm); - if (strcmp(buf, argv[i])) + int len = strlen(tp->args[i].name); + + if (strncmp(argv[i], tp->args[i].name, len) || + argv[i][len] != '=' || + strcmp(argv[i] + len + 1, tp->args[i].comm)) return false; } return true; From a9d6fb284039a5d3858a1d9f9a0d7e46cfb7c2d4 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Mon, 20 Jul 2026 19:12:20 +0900 Subject: [PATCH 2/4] tracing/probes: Prevent out-of-bounds write in __trace_probe_log_err() If trace_probe_log.argc is 0 in __trace_probe_log_err(), the loop constructing the command string will not execute and p will remain equal to command. Writing to *(p - 1) will cause an out-of-bounds access before command. This should not happen, but better to be treated. Reject if trace_probe_log.argc is 0. Link: https://lore.kernel.org/all/178454233992.290363.18323091580600697731.stgit@devnote2/ Fixes: ab105a4fb894 ("tracing: Use tracing error_log with probe events") Cc: stable@vger.kernel.org Assisted-by: Antigravity:gemini-3.5-flash Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_probe.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index 95e3d072321f..49daa3cc2a45 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -188,7 +188,7 @@ void __trace_probe_log_err(int offset, int err_type) lockdep_assert_held(&dyn_event_ops_mutex); - if (!trace_probe_log.argv) + if (!trace_probe_log.argv || !trace_probe_log.argc) return; /* Recalculate the length and allocate buffer */ From 8ce20bfba48902e1382187cd1a852f7cf3a1e739 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Mon, 20 Jul 2026 19:12:29 +0900 Subject: [PATCH 3/4] tracing/probes: Fix potential underflow in LEN_OR_ZERO macro In __set_print_fmt(), LEN_OR_ZERO is defined as (len ? len - pos : 0). If len is non-zero but smaller than pos, len - pos evaluates to a negative integer. When passed as a size argument to snprintf(), this negative value is cast to a large unsigned size_t, bypassing buffer size limits. Ensure len > pos before subtracting to avoid integer underflow. Link: https://lore.kernel.org/all/178454234934.290363.15247317871499514139.stgit@devnote2/ Fixes: 5bf652aaf46c ("tracing/probes: Integrate duplicate set_print_fmt()") Cc: stable@vger.kernel.org Assisted-by: Antigravity:gemini-3.5-flash Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_probe.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index 49daa3cc2a45..506e6037e163 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -2013,7 +2013,7 @@ int traceprobe_update_arg(struct probe_arg *arg) } /* When len=0, we just calculate the needed length */ -#define LEN_OR_ZERO (len ? len - pos : 0) +#define LEN_OR_ZERO (len > pos ? len - pos : 0) static int __set_print_fmt(struct trace_probe *tp, char *buf, int len, enum probe_print_type ptype) { From f418d68d71fd4a0a9cef92377bc8c4c3334b5b53 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Mon, 20 Jul 2026 19:12:38 +0900 Subject: [PATCH 4/4] tracing/eprobe: Fix exact system name matching in eprobe_dyn_event_match() eprobe_dyn_event_match() checks if the target event system in argv[0] matches ep->event_system using strncmp(ep->event_system, argv[0], len). However, if ep->event_system is longer than len (e.g. "eprobes" vs "ep/event"), strncmp() still returns 0 because the first len characters match. Check that ep->event_system[len] is '\0' to ensure exact system name matching. Link: https://lore.kernel.org/all/178454235856.290363.14872590900774231133.stgit@devnote2/ Fixes: 7d5fda1c841f ("tracing: Fix event probe removal from dynamic events") Cc: stable@vger.kernel.org Assisted-by: Antigravity:gemini-3.5-flash Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_eprobe.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c index 50518b071414..bcd97cb24ac9 100644 --- a/kernel/trace/trace_eprobe.c +++ b/kernel/trace/trace_eprobe.c @@ -172,7 +172,8 @@ static bool eprobe_dyn_event_match(const char *system, const char *event, if (!slash) return false; - if (strncmp(ep->event_system, argv[0], slash - argv[0])) + if (strncmp(ep->event_system, argv[0], slash - argv[0]) || + ep->event_system[slash - argv[0]] != '\0') return false; if (strcmp(ep->event_name, slash + 1)) return false;