Re: [PATCH] net: dsa: fix unbalanced dsa_switch_tree reference counting
From: Andrew Lunn <andrew@lunn.ch>
Date: 2016-11-25 16:14:38
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On Fri, Nov 25, 2016 at 07:08:53PM +0300, Nikita Yushchenko wrote:
_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@cogentembedded.com>
Hi Nikita
What tree is this against? It should be net. Please make the subject
[patch net] ... so it is clear what tree this is for.
And it should have a fixes-tag
Fixes: 83c0afaec7b7 ("net: dsa: Add new binding implementation")
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Andrew
quoted hunk ↗ jump to hunk
--- 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