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authorSteven Rostedt (Google) <rostedt@goodmis.org>2024-03-04 22:34:33 -0500
committerSteven Rostedt (Google) <rostedt@goodmis.org>2024-03-06 13:27:26 -0500
commit095fe4891282be510af0db1b03587b512c0de31d (patch)
treee1acce266710a4ae05b849543af2ca4e0c8dd56e /kernel
parent6f42249fecb94dfb6514ed241475f748c03d62fb (diff)
tracing: Limit trace_marker writes to just 4K
Limit the max print event of trace_marker to just 4K string size. This must also be less than the amount that can be held by a trace_seq along with the text that is before the output (like the task name, PID, CPU, state, etc). As trace_seq is made to handle large events (some greater than 4K). Make the max size of a trace_marker write event be 4K which is guaranteed to fit in the trace_seq buffer. Link: https://lore.kernel.org/linux-trace-kernel/20240304223433.4ba47dff@gandalf.local.home Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/trace.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8198bfc54b58..d16b95ca58a7 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7293,6 +7293,8 @@ tracing_free_buffer_release(struct inode *inode, struct file *filp)
return 0;
}
+#define TRACE_MARKER_MAX_SIZE 4096
+
static ssize_t
tracing_mark_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *fpos)
@@ -7320,6 +7322,9 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
if ((ssize_t)cnt < 0)
return -EINVAL;
+ if (cnt > TRACE_MARKER_MAX_SIZE)
+ cnt = TRACE_MARKER_MAX_SIZE;
+
meta_size = sizeof(*entry) + 2; /* add '\0' and possible '\n' */
again:
size = cnt + meta_size;
@@ -7328,11 +7333,6 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
if (cnt < FAULTED_SIZE)
size += FAULTED_SIZE - cnt;
- if (size > TRACE_SEQ_BUFFER_SIZE) {
- cnt -= size - TRACE_SEQ_BUFFER_SIZE;
- goto again;
- }
-
buffer = tr->array_buffer.buffer;
event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
tracing_gen_ctx());