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  1. Jan 29, 2023
  2. Aug 04, 2022
    • Peilin Ye's avatar
      audit, io_uring, io-wq: Fix memory leak in io_sq_thread() and io_wqe_worker() · f482aa98
      Peilin Ye authored
      
      Currently @audit_context is allocated twice for io_uring workers:
      
        1. copy_process() calls audit_alloc();
        2. io_sq_thread() or io_wqe_worker() calls audit_alloc_kernel() (which
           is effectively audit_alloc()) and overwrites @audit_context,
           causing:
      
        BUG: memory leak
        unreferenced object 0xffff888144547400 (size 1024):
      <...>
          hex dump (first 32 bytes):
            00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00  ................
            00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
          backtrace:
            [<ffffffff8135cfc3>] audit_alloc+0x133/0x210
            [<ffffffff81239e63>] copy_process+0xcd3/0x2340
            [<ffffffff8123b5f3>] create_io_thread+0x63/0x90
            [<ffffffff81686604>] create_io_worker+0xb4/0x230
            [<ffffffff81686f68>] io_wqe_enqueue+0x248/0x3b0
            [<ffffffff8167663a>] io_queue_iowq+0xba/0x200
            [<ffffffff816768b3>] io_queue_async+0x113/0x180
            [<ffffffff816840df>] io_req_task_submit+0x18f/0x1a0
            [<ffffffff816841cd>] io_apoll_task_func+0xdd/0x120
            [<ffffffff8167d49f>] tctx_task_work+0x11f/0x570
            [<ffffffff81272c4e>] task_work_run+0x7e/0xc0
            [<ffffffff8125a688>] get_signal+0xc18/0xf10
            [<ffffffff8111645b>] arch_do_signal_or_restart+0x2b/0x730
            [<ffffffff812ea44e>] exit_to_user_mode_prepare+0x5e/0x180
            [<ffffffff844ae1b2>] syscall_exit_to_user_mode+0x12/0x20
            [<ffffffff844a7e80>] do_syscall_64+0x40/0x80
      
      Then,
      
        3. io_sq_thread() or io_wqe_worker() frees @audit_context using
           audit_free();
        4. do_exit() eventually calls audit_free() again, which is okay
           because audit_free() does a NULL check.
      
      As suggested by Paul Moore, fix it by deleting audit_alloc_kernel() and
      redundant audit_free() calls.
      
      Fixes: 5bd2182d ("audit,io_uring,io-wq: add some basic audit support to io_uring")
      Suggested-by: default avatarPaul Moore <paul@paul-moore.com>
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarPeilin Ye <peilin.ye@bytedance.com>
      Acked-by: default avatarPaul Moore <paul@paul-moore.com>
      Link: https://lore.kernel.org/r/20220803222343.31673-1-yepeilin.cs@gmail.com
      
      
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      f482aa98
  3. Jul 25, 2022
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