Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
rxrpc: Fix call removal to use RCU safe deletion
Fix rxrpc call removal from the rxnet->calls list to use list_del_rcu() rather than list_del_init() to prevent stuffing up reading /proc/net/rxrpc/calls from potentially getting into an infinite loop.
This, however, means that list_empty() no longer works on an entry that’s been deleted from the list, making it harder to detect prior deletion. Fix this by:
Firstly, make rxrpc_destroy_all_calls() only dump the first ten calls that are unexpectedly still on the list. Limiting the number of steps means there’s no need to call cond_resched() or to remove calls from the list here, thereby eliminating the need for rxrpc_put_call() to check for that.
rxrpc_put_call() can then be fixed to unconditionally delete the call from the list as it is the only place that the deletion occurs.
Details
- Affected product:
- AlmaLinux 9.2 ESU , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , Oracle Linux 7 ELS , TuxCare 9.6 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS
- Affected packages:
- kernel @ 4.18.0 (+8 more)
In the Linux kernel, the following vulnerability has been resolved:
rxrpc: Fix call removal to use RCU safe deletion
Fix rxrpc call removal from the rxnet->calls list to use list_del_rcu() rather than list_del_init() to prevent stuffing up reading /proc/net/rxrpc/calls from potentially getting into an infinite loop.
This, however, means that list_empty() no longer works on an entry that’s been deleted from the list, making it harder to detect prior deletion. Fix this by:
Firstly, make rxrpc_destroy_all_calls() only dump the first ten calls that are unexpectedly still on the list. Limiting the number of steps means there’s no need to call cond_resched() or to remove calls from the list here, thereby eliminating the need for rxrpc_put_call() to check for that.
rxrpc_put_call() can then be fixed to unconditionally delete the call from the list as it is the only place that the deletion occurs.