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net: psp: check for device unregister when creating assoc

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psp_assoc_device_get_locked() obtains a psp_dev reference via
psp_dev_get_for_sock() (which uses psp_dev_tryget() under RCU);
it then acquires psd->lock and drops the reference. Before
the lock is taken, psp_dev_unregister() can run to completion:
take psd->lock, clear out state, unlock, drop the registration
reference.

The expectation is that the lock prevents device unregistration,
but much like with netdevs special care has to be taken when
"upgrading" a reference to a locked device. Add the missing
check if device is still alive. psp_dev_is_registered() exists
already but had no callers, which makes me wonder if I either
forgot to add this or lost the check during refactoring...

Reported-by: Yiming Qian <yimingqian591@gmail.com>
Fixes: 6b46ca260e ("net: psp: add socket security association code")
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260427190606.366101-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski
2026-04-27 12:06:06 -07:00
parent 67d7ae3340
commit b89769f936
1 changed files with 7 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
net/psp/psp_nl.c
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@@ -305,8 +305,13 @@ int psp_assoc_device_get_locked(const struct genl_split_ops *ops,
psd = psp_dev_get_for_sock(socket->sk);
if (psd) {
err = psp_dev_check_access(psd, genl_info_net(info));
if (err) {
/* Extra care needed here, psp_dev_get_for_sock() only gives
* us access to struct psp_dev's memory, which is quite weak.
*/
mutex_lock(&psd->lock);
if (!psp_dev_is_registered(psd) ||
psp_dev_check_access(psd, genl_info_net(info))) {
mutex_unlock(&psd->lock);
psp_dev_put(psd);
psd = NULL;
}
@@ -319,7 +324,6 @@ int psp_assoc_device_get_locked(const struct genl_split_ops *ops,
id = info->attrs[PSP_A_ASSOC_DEV_ID];
if (psd) {
mutex_lock(&psd->lock);
if (id && psd->id != nla_get_u32(id)) {
mutex_unlock(&psd->lock);
NL_SET_ERR_MSG_ATTR(info->extack, id,