regmap: rbtree: Fix overlapping rbnodes.

commit 4e67fb5f5e336250db944921e3c68057d6203034 upstream.

Avoid overlapping register regions by making the initial blklen of a new
node 1. If a register write occurs to a yet uncached register, that is
lower than but near an existing node's base_reg, a new node is created
and it's blklen is set to an arbitrary value (sizeof(*rbnode)). That may
cause this node to overlap with another node. Those nodes should be merged,
but this merge doesn't happen yet, so this patch at least makes the initial
blklen small enough to avoid hitting the wrong node, which may otherwise
lead to severe breakage.

Signed-off-by: David Jander <david@protonic.nl>
Signed-off-by: Mark Brown <broonie@linaro.org>
Signed-off-by: Zhouping Liu <zliu@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/regmap/regcache-rbtree.c b/drivers/base/regmap/regcache-rbtree.c
index 02f490bad30f791f627db78584ca75b691bc6eb7..bb8c3bbc78128ba51e77455df0587fa58aa6d19f 100644 (file)
--- a/drivers/base/regmap/regcache-rbtree.c
+++ b/drivers/base/regmap/regcache-rbtree.c
@@ -362,7 +362,7 @@ static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
                rbnode = kzalloc(sizeof *rbnode, GFP_KERNEL);
                if (!rbnode)
                        return -ENOMEM;
-               rbnode->blklen = sizeof(*rbnode);
+               rbnode->blklen = 1;
                rbnode->base_reg = reg;
                rbnode->block = kmalloc(rbnode->blklen * map->cache_word_size,
                                        GFP_KERNEL);