Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.8 15/45] net: dsa: fix unbalanced dsa_switch_tree reference counting | Date | Fri, 9 Dec 2016 17:20:44 +0100 |
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4.8-stable review patch. If anyone has any objections, please let me know.
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From: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
[ 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 <nikita.yoush@cogentembedded.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/dsa/dsa2.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/net/dsa/dsa2.c +++ b/net/dsa/dsa2.c @@ -28,8 +28,10 @@ static struct dsa_switch_tree *dsa_get_d 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; }
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