Commit 906dbf0d authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Ben Hutchings

tracing: Fix crash from reading trace_pipe with sendfile

commit a29054d9 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@rab.inReported-by: default avatarRabin Vincent <rabin.vincent@gmail.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
parent 5083db77
...@@ -4657,7 +4657,10 @@ static ssize_t tracing_splice_read_pipe(struct file *filp, ...@@ -4657,7 +4657,10 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
spd.nr_pages = i; spd.nr_pages = i;
ret = splice_to_pipe(pipe, &spd); if (i)
ret = splice_to_pipe(pipe, &spd);
else
ret = 0;
out: out:
splice_shrink_spd(&spd); splice_shrink_spd(&spd);
return ret; return ret;
......
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