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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: 5bd2182d58e9 ("audit,io_uring,io-wq: add some basic audit support to io_uring")
Suggested-by: Paul Moore <paul@paul-moore.com>
Cc: stable@vger.kernel.org
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Link: https://lore.kernel.org/r/20220803222343.31673-1-yepeilin.cs@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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