This is a note to let you know that I've just added the patch titled
tracing: Fix crash from reading trace_pipe with sendfile
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tracing-fix-crash-from-reading-trace_pipe-with-sendfile.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a29054d9478d0435ab01b7544da4f674ab13f533 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Red Hat)" <rostedt@xxxxxxxxxxx>
Date: Fri, 18 Mar 2016 15:46:48 -0400
Subject: tracing: Fix crash from reading trace_pipe with sendfile
From: Steven Rostedt (Red Hat) <rostedt@xxxxxxxxxxx>
commit a29054d9478d0435ab01b7544da4f674ab13f533 upstream.
If tracing contains data and the trace_pipe file is read with sendfile(),
then it can trigger a NULL pointer dereference and various BUG_ON within the
VM code.
There's a patch to fix this in the splice_to_pipe() code, but it's also a
good idea to not let that happen from trace_pipe either.
Link: http://lkml.kernel.org/r/1457641146-9068-1-git-send-email-rabin@xxxxxx
Reported-by: Rabin Vincent <rabin.vincent@xxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/trace/trace.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4949,7 +4949,10 @@ static ssize_t tracing_splice_read_pipe(
spd.nr_pages = i;
- ret = splice_to_pipe(pipe, &spd);
+ if (i)
+ ret = splice_to_pipe(pipe, &spd);
+ else
+ ret = 0;
out:
splice_shrink_spd(&spd);
return ret;
Patches currently in stable-queue which might be from rostedt@xxxxxxxxxxx are
queue-4.4/tracing-fix-trace_printk-to-print-when-not-using-bprintk.patch
queue-4.4/tracing-fix-crash-from-reading-trace_pipe-with-sendfile.patch
queue-4.4/tracing-have-preempt-irqs-off-trace-preempt-disabled-functions.patch
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