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Sat, 04 Jul 2026 19:41:06 -0700 (PDT) Received: from localhost ([111.228.63.84]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2cad6f25f7bsm29082025ad.7.2026.07.04.19.41.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 04 Jul 2026 19:41:06 -0700 (PDT) From: Cen Zhang To: Carlos Maiolino , Hans Holmberg , Damien Le Moal Cc: linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, baijiaju1990@gmail.com, zzzccc427@gmail.com Subject: [PATCH v2] xfs: tear down zoned sysfs before freeing zone info Date: Sun, 5 Jul 2026 10:41:00 +0800 Message-Id: <20260705024100.3398090-1-zzzccc427@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The zoned sysfs directory is currently registered as part of the generic per-mount sysfs setup, but the data it exposes has a narrower lifetime. mp->m_zone_info is allocated later by xfs_mount_zones() and freed by xfs_unmount_zones(), while the zoned sysfs kobject remains registered until xfs_mount_sysfs_del() runs near the end of xfs_unmountfs(). A read of nr_open_zones can therefore enter through the still-live sysfs kobject after xfs_unmount_zones() has freed mp->m_zone_info, leading to a use-after-free in nr_open_zones_show(). Make the zoned sysfs lifetime match the zone allocator lifetime. Create the zoned sysfs directory only after xfs_mount_zones() succeeds, and remove it before xfs_unmount_zones() frees m_zone_info during unmount and mount failure cleanup. Validation reproduced this kernel report: BUG: KASAN: slab-use-after-free in nr_open_zones_show+0x86/0x90 The buggy address belongs to the object at ffff88810b177800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 160 bytes inside of freed 1024-byte region [ffff88810b177800, ffff88810b177c00) Read of size 4 Call trace: print_report+0xcd/0x620 nr_open_zones_show+0x86/0x90 (fs/xfs/xfs_sysfs.c:724) srso_alias_return_thunk+0x5/0xfbef5 __virt_addr_valid+0x20c/0x410 kasan_report+0xdd/0x110 sysfs_kf_seq_show+0x1bd/0x380 seq_read_iter+0x40f/0x11b0 lock_release+0xba/0x260 mark_held_locks+0x40/0x70 vfs_read+0x717/0xce0 __up_read+0x319/0x900 ksys_read+0xf8/0x1c0 do_user_addr_fault+0x3d0/0xbc0 trace_hardirqs_on_prepare+0x23/0xf0 do_syscall_64+0xc8/0x530 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x74/0x7c Allocated by task stack: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 __kmalloc_cache_noprof+0x205/0x460 xfs_mount_zones+0x34c/0x2650 xfs_mountfs+0x1b97/0x1eb0 xfs_fs_fill_super+0xf2b/0x18a0 get_tree_bdev_flags+0x310/0x590 vfs_get_tree+0x8d/0x2e0 __x64_sys_fsconfig+0x61c/0xbc0 do_syscall_64+0xc8/0x530 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x74/0x7c Freed by task stack: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x5f/0x80 kfree+0x20e/0x4c0 xfs_unmountfs+0x2fd/0x390 xfs_fs_put_super+0x60/0x110 generic_shutdown_super+0x143/0x4b0 kill_block_super+0x3b/0x90 xfs_kill_sb+0x12/0x50 deactivate_locked_super+0xa7/0x160 cleanup_mnt+0x218/0x420 task_work_run+0x11a/0x1f0 exit_to_user_mode_loop+0x13c/0x4f0 do_syscall_64+0x4a9/0x530 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x74/0x7c Fixes: 62c89988dc19 ("xfs: expose the number of open zones in sysfs") Assisted-by: Codex:gpt-5.5 Signed-off-by: Cen Zhang --- v2: Tear down the zoned sysfs directory before freeing m_zone_info instead of serializing nr_open_zones_show() with s_umount. fs/xfs/xfs_mount.c | 10 +++++++++- fs/xfs/xfs_sysfs.c | 28 +++++++++++++++++----------- fs/xfs/xfs_sysfs.h | 2 ++ 3 files changed, 28 insertions(+), 12 deletions(-) diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c index be90c7b03994..2dcb10bc6187 100644 --- a/fs/xfs/xfs_mount.c +++ b/fs/xfs/xfs_mount.c @@ -1178,6 +1178,9 @@ xfs_mountfs( error = xfs_mount_zones(mp); if (error) goto out_rtunmount; + error = xfs_zoned_sysfs_init(mp); + if (error) + goto out_unmount_zones; } /* @@ -1233,6 +1236,9 @@ xfs_mountfs( out_agresv: xfs_fs_unreserve_ag_blocks(mp); xfs_qm_unmount_quotas(mp); + if (xfs_has_zoned(mp)) + xfs_zoned_sysfs_del(mp); + out_unmount_zones: if (xfs_has_zoned(mp)) xfs_unmount_zones(mp); out_rtunmount: @@ -1323,8 +1329,10 @@ xfs_unmountfs( xfs_zone_gc_stop(mp); xfs_fs_unreserve_ag_blocks(mp); xfs_qm_unmount_quotas(mp); - if (xfs_has_zoned(mp)) + if (xfs_has_zoned(mp)) { + xfs_zoned_sysfs_del(mp); xfs_unmount_zones(mp); + } xfs_rtunmount_inodes(mp); xfs_irele(mp->m_rootip); if (mp->m_metadirip) diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c index 676777064c2d..b62712187324 100644 --- a/fs/xfs/xfs_sysfs.c +++ b/fs/xfs/xfs_sysfs.c @@ -780,6 +780,23 @@ static const struct kobj_type xfs_zoned_ktype = { .default_groups = xfs_zoned_groups, }; +int +xfs_zoned_sysfs_init(struct xfs_mount *mp) +{ + if (!IS_ENABLED(CONFIG_XFS_RT) || !xfs_has_zoned(mp)) + return 0; + + return xfs_sysfs_init(&mp->m_zoned_kobj, &xfs_zoned_ktype, + &mp->m_kobj, "zoned"); +} + +void +xfs_zoned_sysfs_del(struct xfs_mount *mp) +{ + if (IS_ENABLED(CONFIG_XFS_RT) && xfs_has_zoned(mp)) + xfs_sysfs_del(&mp->m_zoned_kobj); +} + int xfs_mount_sysfs_init( struct xfs_mount *mp) @@ -820,14 +837,6 @@ xfs_mount_sysfs_init( if (error) goto out_remove_error_dir; - if (IS_ENABLED(CONFIG_XFS_RT) && xfs_has_zoned(mp)) { - /* .../xfs//zoned/ */ - error = xfs_sysfs_init(&mp->m_zoned_kobj, &xfs_zoned_ktype, - &mp->m_kobj, "zoned"); - if (error) - goto out_remove_error_dir; - } - return 0; out_remove_error_dir: @@ -846,9 +855,6 @@ xfs_mount_sysfs_del( struct xfs_error_cfg *cfg; int i, j; - if (IS_ENABLED(CONFIG_XFS_RT) && xfs_has_zoned(mp)) - xfs_sysfs_del(&mp->m_zoned_kobj); - for (i = 0; i < XFS_ERR_CLASS_MAX; i++) { for (j = 0; j < XFS_ERR_ERRNO_MAX; j++) { cfg = &mp->m_error_cfg[i][j]; diff --git a/fs/xfs/xfs_sysfs.h b/fs/xfs/xfs_sysfs.h index 1622fe80ad3e..25e5f8fae2f3 100644 --- a/fs/xfs/xfs_sysfs.h +++ b/fs/xfs/xfs_sysfs.h @@ -53,6 +53,8 @@ xfs_sysfs_del( } int xfs_mount_sysfs_init(struct xfs_mount *mp); +int xfs_zoned_sysfs_init(struct xfs_mount *mp); +void xfs_zoned_sysfs_del(struct xfs_mount *mp); void xfs_mount_sysfs_del(struct xfs_mount *mp); #endif /* __XFS_SYSFS_H__ */ -- 2.43.0