Red Hat Security Advisory: kernel security update

Important

A use-after-free flaw was found in ip6_autoflowlabel in the Linux kernel's net/ipv6/ip6_output.c code. In this flaw an attacker can cause a denial of service (DoS) attack.

CWE-825 - Expired Pointer Dereference

A use-after-free flaw was found in ip6_finish_output2 in net/ipv6/ip6_output.c in ipv6 access. This flaw could allow an attacker to crash the system at device disconnect. This vulnerability could even lead to a kernel information leak problem.

CWE-825 - Expired Pointer Dereference

In the Linux kernel, the following vulnerability has been resolved: net: use dst_dev_rcu() in sk_setup_caps() Use RCU to protect accesses to dst->dev from sk_setup_caps() and sk_dst_gso_max_size(). Also use dst_dev_rcu() in ip6_dst_mtu_maybe_forward(), and ip_dst_mtu_maybe_forward(). ip4_dst_hoplimit() can use dst_dev_net_rcu().

CWE-416 - Use After Free

In the Linux kernel, the following vulnerability has been resolved: nbd: defer config unlock in nbd_genl_connect There is one use-after-free warning when running NBD_CMD_CONNECT and NBD_CLEAR_SOCK: nbd_genl_connect nbd_alloc_and_init_config // config_refs=1 nbd_start_device // config_refs=2 set NBD_RT_HAS_CONFIG_REF open nbd // config_refs=3 recv_work done // config_refs=2 NBD_CLEAR_SOCK // config_refs=1 close nbd // config_refs=0 refcount_inc -> uaf ------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 24 PID: 1014 at lib/refcount.c:25 refcount_warn_saturate+0x12e/0x290 nbd_genl_connect+0x16d0/0x1ab0 genl_family_rcv_msg_doit+0x1f3/0x310 genl_rcv_msg+0x44a/0x790 The issue can be easily reproduced by adding a small delay before refcount_inc(&nbd->config_refs) in nbd_genl_connect(): mutex_unlock(&nbd->config_lock); if (!ret) { set_bit(NBD_RT_HAS_CONFIG_REF, &config->runtime_flags); + printk("before sleep\n"); + mdelay(5 * 1000); + printk("after sleep\n"); refcount_inc(&nbd->config_refs); nbd_connect_reply(info, nbd->index); }

CWE-911 - Improper Update of Reference Count

In the Linux kernel, the following vulnerability has been resolved: crypto: asymmetric_keys - prevent overflow in asymmetric_key_generate_id Use check_add_overflow() to guard against potential integer overflows when adding the binary blob lengths and the size of an asymmetric_key_id structure and return ERR_PTR(-EOVERFLOW) accordingly. This prevents a possible buffer overflow when copying data from potentially malicious X.509 certificate fields that can be arbitrarily large, such as ASN.1 INTEGER serial numbers, issuer names, etc.

CWE-190 - Integer Overflow or Wraparound