Linux Kernel Memory Leak Vulnerability in mmap Region Handling

A memory leak vulnerability has been identified in the Linux kernel's handling of memory mappings. This issue arises in the __mmap_region() function, where a new shared memory file allocated to back a mapping is not properly released if an error occurs during the mapping process. The vulnerability can be reproduced using fault injection.

Impact

Exploitation of this vulnerability leads to a memory leak, where allocated memory is not properly released, potentially causing increased memory usage and degradation of system performance.

Reproduction

The vulnerability can be reproduced by mapping /dev/zero with the MAP_SHARED flag. This triggers the allocation of a new shared memory file. If the __mmap_new_vma() function fails, the newly allocated file is not released, causing a memory leak. This failure can be induced by using the fault injection feature of the syzkaller fuzzer, specifically by forcing a failure named 'failslab'.

Remediation

Users can upgrade to the latest version of the Linux kernel where this vulnerability has been addressed.