From: Zijun Hu <quic_zijuhu@quicinc.com> stable inclusion from stable-v6.6.78 commit 993121481b5a87829f1e8163f47158b72679f309 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBPC90 CVE: CVE-2025-21745 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... ------------------ commit d1248436cbef1f924c04255367ff4845ccd9025e upstream. blkcg_fill_root_iostats() iterates over @block_class's devices by class_dev_iter_(init|next)(), but does not end iterating with class_dev_iter_exit(), so causes the class's subsystem refcount leakage. Fix by ending the iterating with class_dev_iter_exit(). Fixes: ef45fe470e1e ("blk-cgroup: show global disk stats in root cgroup io.stat") Reviewed-by: Michal Koutný <mkoutny@suse.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: stable@vger.kernel.org Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com> Link: https://lore.kernel.org/r/20250105-class_fix-v6-2-3a2f1768d4d4@quicinc.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Zheng Qixing <zhengqixing@huawei.com> --- block/blk-cgroup.c | 1 + 1 file changed, 1 insertion(+) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 7809546cd418..37e0b92e2e87 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -1139,6 +1139,7 @@ static void blkcg_fill_root_iostats(void) blkg_iostat_set(&blkg->iostat.cur, &tmp); u64_stats_update_end_irqrestore(&blkg->iostat.sync, flags); } + class_dev_iter_exit(&iter); } static void blkcg_print_one_stat(struct blkcg_gq *blkg, struct seq_file *s) -- 2.39.2