On Thu, Aug 4, 2022 at 10:32 AM Jens Axboe <axboe@xxxxxxxxx> wrote:
> On 8/4/22 7:51 AM, Paul Moore wrote:
> > On Wed, Aug 3, 2022 at 6:24 PM Peilin Ye <yepeilin.cs@xxxxxxxxx> wrote:
> >>
> >> From: Peilin Ye <peilin.ye@xxxxxxxxxxxxx>
> >>
> >> 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@xxxxxxxxxxxxxx>
> >> Cc: stable@xxxxxxxxxxxxxxx
> >> Signed-off-by: Peilin Ye <peilin.ye@xxxxxxxxxxxxx>
> >> ---
> >> Change since v1:
> >> - Delete audit_alloc_kernel() (Paul Moore)
> >>
> >> fs/io-wq.c | 3 ---
> >> fs/io_uring.c | 4 ----
> >> include/linux/audit.h | 5 -----
> >> kernel/auditsc.c | 25 -------------------------
> >> 4 files changed, 37 deletions(-)
> >
> > This looks good to me, thanks! Although it looks like the io_uring
> > related changes will need to be applied by hand as they are pointing
> > to the old layout under fs/ as opposed to the newer layout in
> > io_uring/ introduced during this merge window.
> >
> > Jens, did you want to take this via the io_uring tree or should I take
> > it via the audit tree? If the latter, an ACK would be appreciated, if
> > the former my ACK is below.
> >
> > Acked-by: Paul Moore <paul@xxxxxxxxxxxxxx>
>
> Probably better if I take it, since I need to massage it into the
> current tree anyway. We can then use this one as the base for the stable
> backports that are going to be required.
Sounds good to me, thanks everyone.
--
paul-moore.com
