CVE-2024-36484: 
Linux Kernel vulnerability analysis and mitigation

CVE-2024-36484 affects the Linux kernel's networking subsystem, specifically related to socket state checking during accept operations. The vulnerability was discovered when a warning was triggered in the __inet_accept function at net/ipv4/af_inet.c. The issue occurs when shutdown() is called before entering listener status, causing the child socket to reach the accept syscall in FIN_WAIT1 status (Kernel Git).

The vulnerability stems from an overly restrictive socket state check in the __inet_accept function. The issue was introduced after commit 94062790aedb ("tcp: defer shutdown(SEND_SHUTDOWN) for TCP_SYN_RECV sockets"), which caused the socket state validation to fail when a socket enters FIN_WAIT1 status. The fix involves relaxing the existing assertion in __inet_accept() to allow additional valid socket states including FIN_WAIT1, FIN_WAIT2, CLOSING, CLOSE_WAIT, and CLOSE (Kernel Git).

The vulnerability can trigger a kernel warning when specific socket operations are performed in a certain sequence. While this primarily affects system stability, it could potentially lead to denial of service conditions in networked applications that rely on specific socket state transitions (Ubuntu Security).

The vulnerability can be triggered by invoking shutdown() before entering the listener status on a socket. This specific sequence of operations causes the child socket to reach the accept syscall in an unexpected state, triggering the kernel warning (Kernel Git).

The issue has been fixed in various Linux kernel versions through a patch that relaxes the socket state check at accept time. Users should update their systems to the patched kernel versions. For Ubuntu users, this includes updating to linux-image-5.15.0-1078-azure version 5.15.0-1078.87~20.04.1 for Ubuntu 20.04 LTS (Ubuntu Security).