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Code Issues Releases Wiki Activity

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>
This commit is contained in:
Steven Rostedt (Google) 2024-03-04 22:34:33 -05:00
parent 6f42249fec
commit 095fe48912
1 changed files with 5 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
kernel/trace/trace.c
View File

@ -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());