From: Nikita Yushchenko Date: Mon, 28 Nov 2016 06:48:48 +0000 (+0300) Subject: net: dsa: fix unbalanced dsa_switch_tree reference counting X-Git-Tag: v4.8.14~31 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=aa239369bdfa73290be0f743a22c637cfee1967b;p=thirdparty%2Fkernel%2Fstable.git net: dsa: fix unbalanced dsa_switch_tree reference counting [ Upstream commit 7a99cd6e213685b78118382e6a8fed506c82ccb2 ] _dsa_register_switch() gets a dsa_switch_tree object either via dsa_get_dst() or via dsa_add_dst(). Former path does not increase kref in returned object (resulting into caller not owning a reference), while later path does create a new object (resulting into caller owning a reference). The rest of _dsa_register_switch() assumes that it owns a reference, and calls dsa_put_dst(). This causes a memory breakage if first switch in the tree initialized successfully, but second failed to initialize. In particular, freed dsa_swith_tree object is left referenced by switch that was initialized, and later access to sysfs attributes of that switch cause OOPS. To fix, need to add kref_get() call to dsa_get_dst(). Fixes: 83c0afaec7b7 ("net: dsa: Add new binding implementation") Signed-off-by: Nikita Yushchenko Reviewed-by: Andrew Lunn Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c index f30bad9678f0d..3bdecd2f9b88a 100644 --- a/net/dsa/dsa2.c +++ b/net/dsa/dsa2.c @@ -28,8 +28,10 @@ static struct dsa_switch_tree *dsa_get_dst(u32 tree) struct dsa_switch_tree *dst; list_for_each_entry(dst, &dsa_switch_trees, list) - if (dst->tree == tree) + if (dst->tree == tree) { + kref_get(&dst->refcount); return dst; + } return NULL; }