An attacker can send a notify request that causes a new secondary domain to be added to the bind backend, but causes said backend to update its configuration to an invalid one, leading to the backend no longer able to run on the next restart, requiring manual operation to fix it.
A rogue primary server may cause file descriptor exhaustion and eventually a denial of service, when a PowerDNS secondary server forwards a DNS update request to it.
In the Linux kernel, the following vulnerability has been resolved:
perf: Make sure to use pmu_ctx->pmu for groups
Oliver reported that x86_pmu_del() ended up doing an out-of-bound memory access
when group_sched_in() fails and needs to roll back.
This *should* be handled by the transaction callbacks, but he found that when
the group leader is a software event, the transaction handlers of the wrong PMU
are used. Despite the move_group case in perf_event_open() and group_sched_in()
using pmu_ctx->pmu.
Turns out, inherit uses event->pmu to clone the events, effectively undoing the
move_group case for all inherited contexts. Fix this by also making inherit use
pmu_ctx->pmu, ensuring all inherited counters end up in the same pmu context.
Similarly, __perf_event_read() should use equally use pmu_ctx->pmu for the
group case.
In the Linux kernel, the following vulnerability has been resolved:
cxl/region: Fix leakage in __construct_region()
Failing the first sysfs_update_group() needs to explicitly
kfree the resource as it is too early for cxl_region_iomem_release()
to do so.
In the Linux kernel, the following vulnerability has been resolved:
cxl/port: Fix use after free of parent_port in cxl_detach_ep()
cxl_detach_ep() is called during bottom-up removal when all CXL memory
devices beneath a switch port have been removed. For each port in the
hierarchy it locks both the port and its parent, removes the endpoint,
and if the port is now empty, marks it dead and unregisters the port
by calling delete_switch_port(). There are two places during this work
where the parent_port may be used after freeing:
First, a concurrent detach may have already processed a port by the
time a second worker finds it via bus_find_device(). Without pinning
parent_port, it may already be freed when we discover port->dead and
attempt to unlock the parent_port. In a production kernel that's a
silent memory corruption, with lock debug, it looks like this:
[]DEBUG_LOCKS_WARN_ON(__owner_task(owner) != get_current())
[]WARNING: kernel/locking/mutex.c:949 at __mutex_unlock_slowpath+0x1ee/0x310
[]Call Trace:
[]mutex_unlock+0xd/0x20
[]cxl_detach_ep+0x180/0x400 [cxl_core]
[]devm_action_release+0x10/0x20
[]devres_release_all+0xa8/0xe0
[]device_unbind_cleanup+0xd/0xa0
[]really_probe+0x1a6/0x3e0
Second, delete_switch_port() releases three devm actions registered
against parent_port. The last of those is unregister_port() and it
calls device_unregister() on the child port, which can cascade. If
parent_port is now also empty the device core may unregister and free
it too. So by the time delete_switch_port() returns, parent_port may
be free, and the subsequent device_unlock(&parent_port->dev) operates
on freed memory. The kernel log looks same as above, with a different
offset in cxl_detach_ep().
Both of these issues stem from the absence of a lifetime guarantee
between a child port and its parent port.
Establish a lifetime rule for ports: child ports hold a reference to
their parent device until release. Take the reference when the port
is allocated and drop it when released. This ensures the parent is
valid for the full lifetime of the child and eliminates the use after
free window in cxl_detach_ep().
This is easily reproduced with a reload of cxl_acpi in QEMU with CXL
devices present.
An attacker can create a large number of concurrent DoQ or DoH3 connections, causing unlimited memory allocation in DNSdist and leading to a denial of service. DOQ and DoH3 are disabled by default.
A client can trigger excessive memory allocation by generating a lot of queries that are routed to an overloaded DoH backend, causing queries to accumulate into a buffer that will not be released until the end of the connection.
A client can trigger excessive memory allocation by generating a lot of errors responses over a single DoQ and DoH3 connection, as some resources were not properly released until the end of the connection.