CVE-2023-53623: 
Linux Kernel vulnerability analysis and mitigation

A race condition vulnerability has been identified in the Linux kernel's memory management subsystem (CVE-2023-53623). The issue affects the swapinfostruct handling between swapoff and getswappages() operations. The vulnerability was discovered in versions after stable 5.10.y (NVD).

The vulnerability stems from a synchronization issue where si->lock must be held when deleting the si from the available list. Without proper locking, another thread can re-add the si to the available list, leading to memory corruption. The race condition occurs in the swapoff path where one core can delete from the available list while another core attempts to acquire locks and re-add the si, resulting in potential memory corruption when the swap is later reused (NVD).

The vulnerability can trigger massive warning messages inside getswappages() under specific conditions, such as concurrent madvise(MADVPAGEOUT) calls on memory blocks while performing multiple swapon-swapoff operations. In worst-case scenarios, this can lead to system panic and memory corruption, particularly when memory used by si is kept in swapinfo[] after turning off a swap (NVD).

The fix involves ensuring that si->lock is held before calling 'delfromavaillist()' to prevent other threads from seeing the si as deleted and SWPWRITEOK cleared together, which prevents reinsertion (NVD).