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Date: Fri, 25 Nov 2016 19:08:53 +0300 From: Nikita Yushchenko <nikita.yoush@...entembedded.com> To: Andrew Lunn <andrew@...n.ch>, Vivien Didelot <vivien.didelot@...oirfairelinux.com>, Florian Fainelli <f.fainelli@...il.com>, "David S. Miller" <davem@...emloft.net>, John Crispin <john@...ozen.org>, Wei Yongjun <yongjun_wei@...ndmicro.com.cn>, netdev@...r.kernel.org, linux-kernel@...r.kernel.org Cc: Chris Healy <cphealy@...il.com>, Nikita Yushchenko <nikita.yoush@...entembedded.com> Subject: [PATCH] net: dsa: fix unbalanced dsa_switch_tree reference counting _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(). Signed-off-by: Nikita Yushchenko <nikita.yoush@...entembedded.com> --- net/dsa/dsa2.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c index f8a7d9aab437..5fff951a0a49 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; } -- 2.1.4
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