diff options
| author | David Carlier <devnexen@gmail.com> | 2026-07-09 23:18:58 +0100 |
|---|---|---|
| committer | Stefan Schmidt <stefan@datenfreihafen.org> | 2026-09-02 10:26:47 +0200 |
| commit | 979d5b8de8ed4e1f997aef12da5694b99be7b871 (patch) | |
| tree | 69f8a8a75772b67660cb9838d8e16006d45995ae /drivers | |
| parent | bf79662bc85e820ac3b846e2f347da29fbf6ac95 (diff) | |
ieee802154: hwsim: serialize pib updates to fix double-free
hwsim_update_pib() does an unserialized read-swap-free of phy->pib:
pib_old = rtnl_dereference(phy->pib);
...
rcu_assign_pointer(phy->pib, pib);
kfree_rcu(pib_old, rcu);
It assumes the RTNL is held, but ->set_channel is not always called
under it: the mac802154 scan worker changes channels via
drv_set_channel() without the RTNL. Such an update can race an
RTNL-held one on the same phy; both read the same pib_old and both
kfree_rcu() it, double-freeing the object. With SLUB percpu sheaves
batching kfree_rcu(), this surfaces as a KASAN invalid-free in
rcu_free_sheaf().
struct hwsim_phy has no lock for pib. Add one and make the swap atomic
with rcu_replace_pointer() under it, dropping the misleading
rtnl_dereference().
Reported-by: syzbot+60332fd095f8bb2946ad@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=60332fd095f8bb2946ad
Fixes: f25da51fdc38 ("ieee802154: hwsim: add replacement for fakelb")
Signed-off-by: David Carlier <devnexen@gmail.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/20260709221858.158063-1-devnexen@gmail.com
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/net/ieee802154/mac802154_hwsim.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/drivers/net/ieee802154/mac802154_hwsim.c b/drivers/net/ieee802154/mac802154_hwsim.c index 6daa0f198b9f..a9bd1555d2dc 100644 --- a/drivers/net/ieee802154/mac802154_hwsim.c +++ b/drivers/net/ieee802154/mac802154_hwsim.c @@ -72,6 +72,8 @@ struct hwsim_phy { struct ieee802154_hw *hw; u32 idx; + /* Serializes phy->pib_updates. */ + spinlock_t pib_lock; struct hwsim_pib __rcu *pib; bool suspended; @@ -102,8 +104,6 @@ static int hwsim_update_pib(struct ieee802154_hw *hw, u8 page, u8 channel, if (!pib) return -ENOMEM; - pib_old = rtnl_dereference(phy->pib); - pib->page = page; pib->channel = channel; pib->filt.short_addr = filt->short_addr; @@ -112,7 +112,10 @@ static int hwsim_update_pib(struct ieee802154_hw *hw, u8 page, u8 channel, pib->filt.pan_coord = filt->pan_coord; pib->filt_level = filt_level; - rcu_assign_pointer(phy->pib, pib); + spin_lock_bh(&phy->pib_lock); + pib_old = rcu_replace_pointer(phy->pib, pib, + lockdep_is_held(&phy->pib_lock)); + spin_unlock_bh(&phy->pib_lock); kfree_rcu(pib_old, rcu); return 0; } @@ -952,6 +955,7 @@ static int hwsim_add_one(struct genl_info *info, struct device *dev, goto err_pib; } + spin_lock_init(&phy->pib_lock); pib->channel = 13; pib->filt.short_addr = cpu_to_le16(IEEE802154_ADDR_BROADCAST); pib->filt.pan_id = cpu_to_le16(IEEE802154_PANID_BROADCAST); |