The Linux kernel's slab allocator had a flaw where enabling only SLAB_RED_ZONE without SLAB_STORE_USER caused improper zeroing of allocated memory. Normally, when zeroing is requested, the entire object size is zeroed to meet krealloc()'s __GFP_ZERO guarantees. However, with red zoning enabled alone, the code incorrectly zeroed the entire object size instead of just the requested size, potentially violating the zeroing contract. The vulnerability was fixed by using slub_debug_orig_size() to accurately determine if the requested size is tracked, ensuring correct zeroing behavior regardless of red zoning status.

This vulnerability could lead to scenarios where memory zeroing guarantees provided by krealloc() with __GFP_ZERO are not met, potentially exposing uninitialized memory contents. However, no known exploits in the wild have been reported. The impact is limited to kernel memory management behavior and may affect kernel stability or security depending on usage.

A fix has been implemented in the Linux kernel source to address this issue. Users should apply the official kernel updates that include this patch. Since this is a kernel-level vulnerability, updating to a fixed kernel version is the recommended remediation. Patch status is not explicitly confirmed here; users should consult the Linux kernel vendor advisory or distribution security updates for the exact fixed versions and apply them accordingly.