From c1acb4ac1a892cf08d27efcb964ad281728b0545 Mon Sep 17 00:00:00 2001 From: Qiujun Huang Date: Fri, 30 Oct 2020 00:19:05 +0800 Subject: tracing: Fix out of bounds write in get_trace_buf The nesting count of trace_printk allows for 4 levels of nesting. The nesting counter starts at zero and is incremented before being used to retrieve the current context's buffer. But the index to the buffer uses the nesting counter after it was incremented, and not its original number, which in needs to do. Link: https://lkml.kernel.org/r/20201029161905.4269-1-hqjagain@gmail.com Cc: stable@vger.kernel.org Fixes: 3d9622c12c887 ("tracing: Add barrier to trace_printk() buffer nesting modification") Signed-off-by: Qiujun Huang Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 528971714fc6..daa96215e294 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3132,7 +3132,7 @@ static char *get_trace_buf(void) /* Interrupts must see nesting incremented before we use the buffer */ barrier(); - return &buffer->buffer[buffer->nesting][0]; + return &buffer->buffer[buffer->nesting - 1][0]; } static void put_trace_buf(void) -- cgit v1.2.3