Commit c1acb4ac authored Oct 30, 2020 by Qiujun Huang Committed by Steven Rostedt (VMware) Nov 02, 2020

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: 3d9622c1 ("tracing: Add barrier to trace_printk() buffer nesting modification")
Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

parent 3cea11cd

kernel/trace/trace.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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)

Admin message