From 1fdc4164e488916402badddbb1f51e9380dabb91 Mon Sep 17 00:00:00 2001 From: Kyle Zeng Date: Fri, 23 Oct 2026 10:46:20 -0700 Subject: tracing: Reject incomplete event filter expressions A non-empty expression normally finishes in predicate_parse()'s inner loop, which resolves the pending logical operators before jumping to finalization. If the input ends after an operator, possibly followed by unary '!' tokens, the outer loop instead falls through with unresolved operator state. For example, "common_pid == 1 || common_pid == 2 &&" leaves prog[0].target equal to -1. The second pass then reads prog[-1] before the forward-jump check can reject it. Depending on adjacent slab contents, it can also copy an out-of-bounds word into a branch target that passes the forward-only check. A self-targeted perf tracepoint counting event can reach this path through PERF_EVENT_IOC_SET_FILTER. Reject the outer-loop fallthrough when a predicate has already been parsed. This ensures that non-empty expressions only reach finalization after the inner loop has resolved their operators. Keep the existing no-filter error for input that has no predicates. Add a regression test for trailing logical operators and unary negations. Fixes: 80765597bc587 ("tracing: Rewrite filter logic to be simpler and faster") Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20261023174620.91969-1-kylebot@openai.com Assisted-by: Codex:gpt-6-astra Acked-by: Masami Hiramatsu (Google) Tested-by: JongHyuk Kim(MalHyuk) Signed-off-by: Kyle Zeng Signed-off-by: Steven Rostedt --- kernel/trace/trace_events_filter.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index b3b13700abce..5e74d2dae40a 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -598,6 +598,12 @@ predicate_parse(const char *str, int nr_parens, int nr_preds, top--; /* #12 */ } } + /* Only the inner loop can complete a non-empty expression. */ + if (N) { + ret = -EINVAL; + parse_error(pe, FILT_ERR_INVALID_FILTER, ptr - str); + goto out_free; + } out: if (top != op_stack) { /* Too many '(' */ -- cgit v1.2.3