# \[PATCH v4 08/15\] tracing/filters: Reject unsupported field sizes in parse\_pred() - From: Masami Hiramatsu (Google) \ - Date: 2026-10-29 01:38:43 - List: linux-trace-kernel - Page: https://ratatoskr.run/linux-trace-kernel/2026/10/17824029 - Thread: https://ratatoskr.run/linux-trace-kernel/2026/10/17824014/t.md ```text From: Masami Hiramatsu (Google) Prior to commit 80765597bc58 ("tracing: Rewrite filter logic to be simpler and faster"), parse_pred() checked whether select_comparison_fn() returned NULL and failed with FILT_ERR_INVALID_OP and -EINVAL. That check was lost during the rewrite, and commit 3cbec9d7b93d ("tracing/filters: Enable filtering a scalar field by a cpumask") similarly omitted a default error case when matching field->size for CPUS{} comparisons. If a non-string field (FILTER_OTHER) has a size other than 1, 2, 4, or 8 (such as a fixed-size integer array field), pred->fn_num remains FILTER_PRED_FN_NOP (0) and parse_pred() returns success. Subsequently, update_preds() rejects FILTER_PRED_FN_NOP via WARN_ON_ONCE() and returns -EINVAL without setting a parse_error() message, triggering a kernel warning from user-supplied filter input. Restore the check for FILTER_PRED_FN_NOP in both the numeric scalar and CPUS{} branches of parse_pred() and report FILT_ERR_INVALID_OP. Fixes: 80765597bc58 ("tracing: Rewrite filter logic to be simpler and faster") Fixes: 3cbec9d7b93d ("tracing/filters: Enable filtering a scalar field by a cpumask") Cc: Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_events_filter.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index a645af9eb1f8..40efcef94e02 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -2013,6 +2013,10 @@ static int parse_pred(const char *str, void *data, break; } } + if (pred->fn_num == FILTER_PRED_FN_NOP) { + parse_error(pe, FILT_ERR_INVALID_OP, pos + i); + goto err_free; + } /* This is either a string, or an integer */ } else if (str[i] == '\'' || str[i] == '"') { @@ -2166,6 +2170,10 @@ static int parse_pred(const char *str, void *data, else { pred->fn_num = select_comparison_fn(pred->op, field->size, field->is_signed); + if (pred->fn_num == FILTER_PRED_FN_NOP) { + parse_error(pe, FILT_ERR_INVALID_OP, pos + i); + goto err_free; + } if (pred->op == OP_NE) pred->not = 1; } ```