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Wong" , Leah Rumancik Subject: [PATCH 6.1 CANDIDATE 16/24] xfs: wait iclog complete before tearing down AIL Date: Fri, 26 Apr 2024 14:55:03 -0700 Message-ID: <20240426215512.2673806-17-leah.rumancik@gmail.com> X-Mailer: git-send-email 2.44.0.769.g3c40516874-goog In-Reply-To: <20240426215512.2673806-1-leah.rumancik@gmail.com> References: <20240426215512.2673806-1-leah.rumancik@gmail.com> Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Guo Xuenan [ Upstream commit 1eb52a6a71981b80f9acbd915acd6a05a5037196 ] Fix uaf in xfs_trans_ail_delete during xlog force shutdown. In commit cd6f79d1fb32 ("xfs: run callbacks before waking waiters in xlog_state_shutdown_callbacks") changed the order of running callbacks and wait for iclog completion to avoid unmount path untimely destroy AIL. But which seems not enough to ensue this, adding mdelay in `xfs_buf_item_unpin` can prove that. The reproduction is as follows. To ensure destroy AIL safely, we should wait all xlog ioend workers done and sync the AIL. ================================================================== BUG: KASAN: use-after-free in xfs_trans_ail_delete+0x240/0x2a0 Read of size 8 at addr ffff888023169400 by task kworker/1:1H/43 CPU: 1 PID: 43 Comm: kworker/1:1H Tainted: G W 6.1.0-rc1-00002-gc28266863c4a #137 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Workqueue: xfs-log/sda xlog_ioend_work Call Trace: dump_stack_lvl+0x4d/0x66 print_report+0x171/0x4a6 kasan_report+0xb3/0x130 xfs_trans_ail_delete+0x240/0x2a0 xfs_buf_item_done+0x7b/0xa0 xfs_buf_ioend+0x1e9/0x11f0 xfs_buf_item_unpin+0x4c8/0x860 xfs_trans_committed_bulk+0x4c2/0x7c0 xlog_cil_committed+0xab6/0xfb0 xlog_cil_process_committed+0x117/0x1e0 xlog_state_shutdown_callbacks+0x208/0x440 xlog_force_shutdown+0x1b3/0x3a0 xlog_ioend_work+0xef/0x1d0 process_one_work+0x6f9/0xf70 worker_thread+0x578/0xf30 kthread+0x28c/0x330 ret_from_fork+0x1f/0x30 Allocated by task 9606: kasan_save_stack+0x1e/0x40 kasan_set_track+0x21/0x30 __kasan_kmalloc+0x7a/0x90 __kmalloc+0x59/0x140 kmem_alloc+0xb2/0x2f0 xfs_trans_ail_init+0x20/0x320 xfs_log_mount+0x37e/0x690 xfs_mountfs+0xe36/0x1b40 xfs_fs_fill_super+0xc5c/0x1a70 get_tree_bdev+0x3c5/0x6c0 vfs_get_tree+0x85/0x250 path_mount+0xec3/0x1830 do_mount+0xef/0x110 __x64_sys_mount+0x150/0x1f0 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Freed by task 9662: kasan_save_stack+0x1e/0x40 kasan_set_track+0x21/0x30 kasan_save_free_info+0x2a/0x40 __kasan_slab_free+0x105/0x1a0 __kmem_cache_free+0x99/0x2d0 kvfree+0x3a/0x40 xfs_log_unmount+0x60/0xf0 xfs_unmountfs+0xf3/0x1d0 xfs_fs_put_super+0x78/0x300 generic_shutdown_super+0x151/0x400 kill_block_super+0x9a/0xe0 deactivate_locked_super+0x82/0xe0 deactivate_super+0x91/0xb0 cleanup_mnt+0x32a/0x4a0 task_work_run+0x15f/0x240 exit_to_user_mode_prepare+0x188/0x190 syscall_exit_to_user_mode+0x12/0x30 do_syscall_64+0x42/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd The buggy address belongs to the object at ffff888023169400 which belongs to the cache kmalloc-128 of size 128 The buggy address is located 0 bytes inside of 128-byte region [ffff888023169400, ffff888023169480) The buggy address belongs to the physical page: page:ffffea00008c5a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888023168f80 pfn:0x23168 head:ffffea00008c5a00 order:1 compound_mapcount:0 compound_pincount:0 flags: 0x1fffff80010200(slab|head|node=0|zone=1|lastcpupid=0x1fffff) raw: 001fffff80010200 ffffea00006b3988 ffffea0000577a88 ffff88800f842ac0 raw: ffff888023168f80 0000000000150007 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888023169300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888023169380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888023169400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888023169480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888023169500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== Disabling lock debugging due to kernel taint Fixes: cd6f79d1fb32 ("xfs: run callbacks before waking waiters in xlog_state_shutdown_callbacks") Signed-off-by: Guo Xuenan Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Signed-off-by: Leah Rumancik --- fs/xfs/xfs_log.c | 36 +++++++++++++++++++++++++----------- 1 file changed, 25 insertions(+), 11 deletions(-) diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index f02a0dd522b3..60b19f6d7077 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -886,6 +886,23 @@ xlog_force_iclog( return xlog_state_release_iclog(iclog->ic_log, iclog, NULL); } +/* + * Cycle all the iclogbuf locks to make sure all log IO completion + * is done before we tear down these buffers. + */ +static void +xlog_wait_iclog_completion(struct xlog *log) +{ + int i; + struct xlog_in_core *iclog = log->l_iclog; + + for (i = 0; i < log->l_iclog_bufs; i++) { + down(&iclog->ic_sema); + up(&iclog->ic_sema); + iclog = iclog->ic_next; + } +} + /* * Wait for the iclog and all prior iclogs to be written disk as required by the * log force state machine. Waiting on ic_force_wait ensures iclog completions @@ -1111,6 +1128,14 @@ xfs_log_unmount( { xfs_log_clean(mp); + /* + * If shutdown has come from iclog IO context, the log + * cleaning will have been skipped and so we need to wait + * for the iclog to complete shutdown processing before we + * tear anything down. + */ + xlog_wait_iclog_completion(mp->m_log); + xfs_buftarg_drain(mp->m_ddev_targp); xfs_trans_ail_destroy(mp); @@ -2113,17 +2138,6 @@ xlog_dealloc_log( xlog_in_core_t *iclog, *next_iclog; int i; - /* - * Cycle all the iclogbuf locks to make sure all log IO completion - * is done before we tear down these buffers. - */ - iclog = log->l_iclog; - for (i = 0; i < log->l_iclog_bufs; i++) { - down(&iclog->ic_sema); - up(&iclog->ic_sema); - iclog = iclog->ic_next; - } - /* * Destroy the CIL after waiting for iclog IO completion because an * iclog EIO error will try to shut down the log, which accesses the