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Test your applicationsUpgrade RHEL:8
kernel-debug
to version 0:4.18.0-477.70.1.el8_8 or higher.
This issue was patched in RHSA-2024:6206
.
Note: Versions mentioned in the description apply only to the upstream kernel-debug
package and not the kernel-debug
package as distributed by RHEL
.
See How to fix?
for RHEL:8
relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
tls: fix missing memory barrier in tls_init
In tls_init(), a write memory barrier is missing, and store-store reordering may cause NULL dereference in tls_{setsockopt,getsockopt}.
CPU0 CPU1
// In tls_init() // In tls_ctx_create() ctx = kzalloc() ctx->sk_proto = READ_ONCE(sk->sk_prot) -(1)
// In update_sk_prot() WRITE_ONCE(sk->sk_prot, tls_prots) -(2)
// In sock_common_setsockopt() READ_ONCE(sk->sk_prot)->setsockopt()
// In tls_{setsockopt,getsockopt}() ctx->sk_proto->setsockopt() -(3)
In the above scenario, when (1) and (2) are reordered, (3) can observe the NULL value of ctx->sk_proto, causing NULL dereference.
To fix it, we rely on rcu_assign_pointer() which implies the release barrier semantic. By moving rcu_assign_pointer() after ctx->sk_proto is initialized, we can ensure that ctx->sk_proto are visible when changing sk->sk_prot.