From 73984137d32bb6e48646daea60ebe1457a01a061 Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Wed, 10 Aug 2016 16:27:38 -0700 Subject: [PATCH] rapidio: dereferencing an error pointer Original patch: https://lkml.org/lkml/2016/8/4/32 If riocm_ch_alloc() fails then we end up dereferencing the error pointer. The problem is that we're not unwinding in the reverse order from how we allocate things so it gets confusing. I've changed this around so now "ch" is NULL when we are done with it after we call riocm_put_channel(). That way we can check if it's NULL and avoid calling riocm_put_channel() on it twice. I renamed err_nodev to err_put_new_ch so that it better reflects what the goto does. Then because we had flipping things around, it means we don't neeed to initialize the pointers to NULL and we can remove an if statement and pull things in an indent level. Link: http://lkml.kernel.org/r/20160805152406.20713-1-alexandre.bounine@idt.com Signed-off-by: Dan Carpenter Signed-off-by: Alexandre Bounine Cc: Matt Porter Cc: Andre van Herk Cc: Barry Wood Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/rapidio/rio_cm.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) diff --git a/drivers/rapidio/rio_cm.c b/drivers/rapidio/rio_cm.c index cecc15a..3fa17ac 100644 --- a/drivers/rapidio/rio_cm.c +++ b/drivers/rapidio/rio_cm.c @@ -1080,8 +1080,8 @@ static int riocm_send_ack(struct rio_channel *ch) static struct rio_channel *riocm_ch_accept(u16 ch_id, u16 *new_ch_id, long timeout) { - struct rio_channel *ch = NULL; - struct rio_channel *new_ch = NULL; + struct rio_channel *ch; + struct rio_channel *new_ch; struct conn_req *req; struct cm_peer *peer; int found = 0; @@ -1155,6 +1155,7 @@ static struct rio_channel *riocm_ch_accept(u16 ch_id, u16 *new_ch_id, spin_unlock_bh(&ch->lock); riocm_put_channel(ch); + ch = NULL; kfree(req); down_read(&rdev_sem); @@ -1172,7 +1173,7 @@ static struct rio_channel *riocm_ch_accept(u16 ch_id, u16 *new_ch_id, if (!found) { /* If peer device object not found, simply ignore the request */ err = -ENODEV; - goto err_nodev; + goto err_put_new_ch; } new_ch->rdev = peer->rdev; @@ -1184,15 +1185,16 @@ static struct rio_channel *riocm_ch_accept(u16 ch_id, u16 *new_ch_id, *new_ch_id = new_ch->id; return new_ch; + +err_put_new_ch: + spin_lock_bh(&idr_lock); + idr_remove(&ch_idr, new_ch->id); + spin_unlock_bh(&idr_lock); + riocm_put_channel(new_ch); + err_put: - riocm_put_channel(ch); -err_nodev: - if (new_ch) { - spin_lock_bh(&idr_lock); - idr_remove(&ch_idr, new_ch->id); - spin_unlock_bh(&idr_lock); - riocm_put_channel(new_ch); - } + if (ch) + riocm_put_channel(ch); *new_ch_id = 0; return ERR_PTR(err); } -- 2.7.4