CyberRota Analysis
AI-GeneratedThe vulnerability affects the Linux kernel's NFS daemon (nfsd), specifically in the handling of the rpc_status_get dumpit function, where a missing read memory barrier can lead to ineffective retry logic on weakly-ordered architectures like ARM and POWER. This flaw may allow the CPU to reorder field reads, potentially exposing inconsistent data during concurrent modifications. System administrators and developers using affected Linux kernel versions should prioritize patching this vulnerability to ensure data integrity and prevent potential exploitation in multi-threaded environments.
Original NVD Description
In the Linux kernel, the following vulnerability has been resolved: nfsd: add missing read barrier to rpc_status_get dumpit seqcount retry The hand-rolled seqcount-like protocol in nfsd_nl_rpc_status_get_dumpit() is missing a read memory barrier (smp_rmb) before its second counter check. The standard kernel read_seqcount_retry() includes smp_rmb() to ensure that all data reads complete before the counter is re-checked. Without this barrier, on weakly-ordered architectures (ARM, POWER), the CPU may reorder field reads past the second counter check, making the retry logic ineffective: it could observe a consistent counter pair while reading fields that have been concurrently modified by the writer. Add smp_rmb() before the second counter check to order the field reads ahead of it, matching the barrier semantics of the standard seqcount read-side. The begin-side smp_load_acquire() already pairs with the smp_store_release() in nfsd_dispatch(); with the smp_rmb() now ordering the field reads, the retry check no longer needs acquire semantics and reads the counter with a plain READ_ONCE(), as read_seqcount_retry() does. [ cel: Use READ_ONCE instead of smp_load_acquire() ]