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| author | Florian Fainelli <f.fainelli@gmail.com> | 2017-06-02 22:05:23 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-06-14 15:07:34 +0200 |
| commit | 223313c9be690577f888976cc6da46a6a43878f6 (patch) | |
| tree | f07e4759f49fc6cc57289b7938ce554a0fbc61bc | |
| parent | a32f7198b20d0aaece709028327469fdbcb8d25a (diff) | |
net: dsa: Fix stale cpu_switch reference after unbind then bind
[ Upstream commit b07ac9894644202614ca87c69f3f45e424a82fef ]
Commit 9520ed8fb841 ("net: dsa: use cpu_switch instead of ds[0]")
replaced the use of dst->ds[0] with dst->cpu_switch since that is
functionally equivalent, however, we can now run into an use after free
scenario after unbinding then rebinding the switch driver.
The use after free happens because we do correctly initialize
dst->cpu_switch the first time we probe in dsa_cpu_parse(), then we
unbind the driver: dsa_dst_unapply() is called, and we rebind again.
dst->cpu_switch now points to a freed "ds" structure, and so when we
finally dereference it in dsa_cpu_port_ethtool_setup(), we oops.
To fix this, simply set dst->cpu_switch to NULL in dsa_dst_unapply()
which guarantees that we always correctly re-assign dst->cpu_switch in
dsa_cpu_parse().
Fixes: 9520ed8fb841 ("net: dsa: use cpu_switch instead of ds[0]")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/dsa/dsa2.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c index 737be6470c7f2..ffaa4fb33d0ac 100644 --- a/net/dsa/dsa2.c +++ b/net/dsa/dsa2.c @@ -440,8 +440,10 @@ static void dsa_dst_unapply(struct dsa_switch_tree *dst) dsa_ds_unapply(dst, ds); } - if (dst->cpu_switch) + if (dst->cpu_switch) { dsa_cpu_port_ethtool_restore(dst->cpu_switch); + dst->cpu_switch = NULL; + } pr_info("DSA: tree %d unapplied\n", dst->tree); dst->applied = false; |