Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=4b3e3d...
Commit: 4b3e3d228429c75d398f1aa24532e468d3220c49
Parent: 4d7a077c0c7bfdba04cf0aa0b79053cf4ebaacf8
Author: Steven Rostedt <srostedt@redhat.com>
AuthorDate: Wed Feb 18 22:50:01 2009 -0500
Committer: Steven Rostedt <srostedt@redhat.com>
CommitDate: Wed Feb 18 22:50:01 2009 -0500
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 <srostedt@redhat.com>
---
kernel/trace/trace_selftest.c | 10 ++++++++++
1 files changed, 10 insertions(+), 0 deletions(-)
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index a7e0ef6..bc8e80a 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);
--
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