From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755251Ab2K3QNi (ORCPT ); Fri, 30 Nov 2012 11:13:38 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:31642 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754794Ab2K3QNf (ORCPT ); Fri, 30 Nov 2012 11:13:35 -0500 X-Authority-Analysis: v=2.0 cv=EshQXFgA c=1 sm=0 a=rXTBtCOcEpjy1lPqhTCpEQ==:17 a=mNMOxpOpBa8A:10 a=Ciwy3NGCPMMA:10 a=eC57RPd7L5cA:10 a=5SG0PmZfjMsA:10 a=bbbx4UPp9XUA:10 a=meVymXHHAAAA:8 a=uXSjbnlxps4A:10 a=20KFwNOVAAAA:8 a=VwQbUJbxAAAA:8 a=wDAzwacqOiJ7wvIdIqAA:9 a=QEXdDO2ut3YA:10 a=jEp0ucaQiEUA:10 a=jeBq3FmKZ4MA:10 a=EJzWNDzxMEWny7dhMFIA:9 a=rXTBtCOcEpjy1lPqhTCpEQ==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 74.67.115.198 Message-Id: <20121130161333.983378567@goodmis.org> User-Agent: quilt/0.60-1 Date: Fri, 30 Nov 2012 11:12:39 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Thomas Gleixner , Frederic Weisbecker Subject: [PATCH 1/2] ring-buffer: Fix NULL pointer if rb_set_head_page() fails References: <20121130161238.909829067@goodmis.org> Content-Disposition: inline; filename=0001-ring-buffer-Fix-NULL-pointer-if-rb_set_head_page-fai.patch Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="00GvhwF7k39YY" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --00GvhwF7k39YY Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable From: Steven Rostedt The function rb_set_head_page() searches the list of ring buffer pages for a the page that has the HEAD page flag set. If it does not find it, it will do a WARN_ON(), disable the ring buffer and return NULL, as this should never happen. But if this bug happens to happen, not all callers of this function can handle a NULL pointer being returned from it. That needs to be fixed. Cc: stable@vger.kernel.org # 3.0+ Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index b979426..ec01803 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1396,6 +1396,8 @@ rb_insert_pages(struct ring_buffer_per_cpu *cpu_buffe= r) struct list_head *head_page_with_bit; =20 head_page =3D &rb_set_head_page(cpu_buffer)->list; + if (!head_page) + break; prev_page =3D head_page->prev; =20 first_page =3D pages->next; @@ -2934,7 +2936,7 @@ unsigned long ring_buffer_oldest_event_ts(struct ring= _buffer *buffer, int cpu) unsigned long flags; struct ring_buffer_per_cpu *cpu_buffer; struct buffer_page *bpage; - unsigned long ret; + unsigned long ret =3D 0; =20 if (!cpumask_test_cpu(cpu, buffer->cpumask)) return 0; @@ -2949,7 +2951,8 @@ unsigned long ring_buffer_oldest_event_ts(struct ring= _buffer *buffer, int cpu) bpage =3D cpu_buffer->reader_page; else bpage =3D rb_set_head_page(cpu_buffer); - ret =3D bpage->page->time_stamp; + if (bpage) + ret =3D bpage->page->time_stamp; raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); =20 return ret; @@ -3260,6 +3263,8 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_bu= ffer) * Splice the empty reader page into the list around the head. */ reader =3D rb_set_head_page(cpu_buffer); + if (!reader) + goto out; cpu_buffer->reader_page->list.next =3D rb_list_head(reader->list.next); cpu_buffer->reader_page->list.prev =3D reader->list.prev; =20 --=20 1.7.10.4 --00GvhwF7k39YY Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQEcBAABAgAGBQJQuNsuAAoJEOdOSU1xswtMrMYH/2jLT4yVqVJu6ZYlTGrFHaby FlvQgcniFfMrUU2KNCdxqZyWNLXSXUM+oug6JimNBmarK3Pa+LwHpRV9uvZswpjK kXQ6SXyuCV3CAyEgN8Zrfl9uZjk5SlHqPIK4SMQC/22AlQDzHWeH7UZstEL/9NO3 KARy/WLdHe244E92ilh0Y4QnN5DTxqMTFTUM1klDyN4IR2U+N+6MArLFjNrmFMCj ipaSzWSep3g37zKT3qOLx8TL91qFixwU7kIGwNnywXUOop/rZCZepOtyCug+wqLY ZdtqTnrfaS+x7QFH1g32FLiDJ81HJnT3BLJfnEVRpca2aGVuKPW/a8sF4lmif+U= =OGWc -----END PGP SIGNATURE----- --00GvhwF7k39YY--