From 4b3e3d228429c75d398f1aa24532e468d3220c49 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 18 Feb 2009 22:50:01 -0500 Subject: tracing: limit the number of loops the ring buffer self test can make Impact: prevent deadlock if ring buffer gets corrupted This patch adds a paranoid check to make sure the ring buffer consumer does not go into an infinite loop. Since the ring buffer has been set to read only, the consumer should not loop for more than the ring buffer size. A check is added to make sure the consumer does not loop more than the ring buffer size. Signed-off-by: Steven Rostedt --- kernel/trace/trace_selftest.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c index a7e0ef662f9..bc8e80a86bc 100644 --- a/kernel/trace/trace_selftest.c +++ b/kernel/trace/trace_selftest.c @@ -23,10 +23,20 @@ static int trace_test_buffer_cpu(struct trace_array *tr, int cpu) { struct ring_buffer_event *event; struct trace_entry *entry; + unsigned int loops = 0; while ((event = ring_buffer_consume(tr->buffer, cpu, NULL))) { entry = ring_buffer_event_data(event); + /* + * The ring buffer is a size of trace_buf_size, if + * we loop more than the size, there's something wrong + * with the ring buffer. + */ + if (loops++ > trace_buf_size) { + printk(KERN_CONT ".. bad ring buffer "); + goto failed; + } if (!trace_valid_entry(entry)) { printk(KERN_CONT ".. invalid entry %d ", entry->type); -- cgit v1.2.3