* Jesper Juhl ([EMAIL PROTECTED]) wrote: > Hi, > > Coverity spotted what looks like a real possible case of using a > variable after it has been freed. > The problem is in kernel/relay.c::relay_open_buf() > > If the code hits "goto free_buf;" it ends up in this code : > > free_buf: > relay_destroy_buf(buf); <--- calls kfree() on 'buf'. > free_name: > kfree(tmpname); > end: > return buf; <-- use after free of 'buf'. > > I read through the callers and they all handle a NULL return > from this function as an error (and hitting the 'free_buf' label > only happens on failure to chan->cb->create_buf_file(), so that > looks like a clear error to me). > > The patch simply sets 'buf' to NULL after the call to > relay_destroy_buf(buf); - as far as I can see that should take > care of the problem. > > The patch also corrects a reference to a documentation file while > I was at it. > > Warning: I don't know this code at all and I've only read through > it quickly to try and work out what to do here, so I'd really > apreciate it if someone who actually knows how this code should > behave could ACK or NACK the patch before it gets merged anywhere > since I did this pretty blind. > > Patch has been compile tested only. > > > Signed-off-by: Jesper Juhl <[EMAIL PROTECTED]>
Yes, the fix seems good. Thanks. Acked-by: Mathieu Desnoyers <[EMAIL PROTECTED]> > --- > > diff --git a/kernel/relay.c b/kernel/relay.c > index a615a8f..c55e399 100644 > --- a/kernel/relay.c > +++ b/kernel/relay.c > @@ -1,7 +1,7 @@ > /* > * Public API and common code for kernel->userspace relay file support. > * > - * See Documentation/filesystems/relayfs.txt for an overview of relayfs. > + * See Documentation/filesystems/relay.txt for an overview. > * > * Copyright (C) 2002-2005 - Tom Zanussi ([EMAIL PROTECTED]), IBM Corp > * Copyright (C) 1999-2005 - Karim Yaghmour ([EMAIL PROTECTED]) > @@ -427,6 +427,7 @@ static struct rchan_buf *relay_open_buf(struct rchan > *chan, unsigned int cpu) > > free_buf: > relay_destroy_buf(buf); > + buf = NULL; > free_name: > kfree(tmpname); > end: > > -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
