From: "Masami Hiramatsu (Google)" <[email protected]> commit 12b80cdbc54cf615b4717a4e8180063408091ea2 upstream.
mmio_trace_rw() and mmio_trace_mapping() retrieve mmio_trace_array into tr and pass it to __trace_mmiotrace_rw() and __trace_mmiotrace_map(). If these functions are invoked while mmio_trace_array is NULL (e.g. before initialization or after disabled), accessing tr->array_buffer.buffer will result in a NULL pointer dereference crash. Fix this by adding an explicit NULL check for tr at the beginning of __trace_mmiotrace_rw() and __trace_mmiotrace_map(). Link: https://patch.msgid.link/178524300062.56416.8362487250709962380.stgit@devnote2 Fixes: f984b51e0779 ("ftrace: add mmiotrace plugin") Assisted-by: Antigravity:gemini-3.6-flash Signed-off-by: Masami Hiramatsu (Google) <[email protected]> Signed-off-by: Steven Rostedt <[email protected]> Signed-off-by: Alexander Martyniuk <[email protected]> --- Backport fix for CVE-2026-80689 kernel/trace/trace_mmiotrace.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c index 74f378fca518..f4ebf7d9cc25 100644 --- a/kernel/trace/trace_mmiotrace.c +++ b/kernel/trace/trace_mmiotrace.c @@ -295,11 +295,15 @@ static void __trace_mmiotrace_rw(struct trace_array *tr, struct mmiotrace_rw *rw) { struct trace_event_call *call = &event_mmiotrace_rw; - struct trace_buffer *buffer = tr->array_buffer.buffer; + struct trace_buffer *buffer; struct ring_buffer_event *event; struct trace_mmiotrace_rw *entry; unsigned int trace_ctx; + if (!tr) + return; + + buffer = tr->array_buffer.buffer; trace_ctx = tracing_gen_ctx_flags(0); event = trace_buffer_lock_reserve(buffer, TRACE_MMIO_RW, sizeof(*entry), trace_ctx); @@ -324,11 +328,15 @@ static void __trace_mmiotrace_map(struct trace_array *tr, struct mmiotrace_map *map) { struct trace_event_call *call = &event_mmiotrace_map; - struct trace_buffer *buffer = tr->array_buffer.buffer; + struct trace_buffer *buffer; struct ring_buffer_event *event; struct trace_mmiotrace_map *entry; unsigned int trace_ctx; + if (!tr) + return; + + buffer = tr->array_buffer.buffer; trace_ctx = tracing_gen_ctx_flags(0); event = trace_buffer_lock_reserve(buffer, TRACE_MMIO_MAP, sizeof(*entry), trace_ctx); -- 2.43.0
