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Date: Thu, 15 Dec 2016 18:46:30 +0000
From: Aaron Tomlin <atomlin@redhat.com>
To: "Luis R. Rodriguez" <mcgrof@kernel.org>
Cc: shuah@kernel.org, jeyu@redhat.com, rusty@rustcorp.com.au,
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Subject: Re: [RFC 02/10] module: fix memory leak on early load_module()
 failures
Message-ID: <20161215184630.mapjqzdox5aqmvsz@atomlin.usersys.redhat.com>
References: <20161208184801.1689-1-mcgrof@kernel.org>
 <20161208194802.2438-1-mcgrof@kernel.org>
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On Thu 2016-12-08 11:48 -0800, Luis R. Rodriguez wrote:
> While looking for early possible module loading failures I was
> able to reproduce a memory leak possible with kmemleak. There
> are a few rare ways to trigger a failure:
>=20
>   o we've run into a failure while processing kernel parameters
>     (parse_args() returns an error)
>   o mod_sysfs_setup() fails
>   o we're a live patch module and copy_module_elf() fails
>=20
> Chances of running into this issue is really low.
>=20
> kmemleak splat:
>=20
> unreferenced object 0xffff9f2c4ada1b00 (size 32):
>   comm "kworker/u16:4", pid 82, jiffies 4294897636 (age 681.816s)
>   hex dump (first 32 bytes):
>     6d 65 6d 73 74 69 63 6b 30 00 00 00 00 00 00 00  memstick0.......
>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>   backtrace:
>     [<ffffffff8c6cfeba>] kmemleak_alloc+0x4a/0xa0
>     [<ffffffff8c200046>] __kmalloc_track_caller+0x126/0x230
>     [<ffffffff8c1bc581>] kstrdup+0x31/0x60
>     [<ffffffff8c1bc5d4>] kstrdup_const+0x24/0x30
>     [<ffffffff8c3c23aa>] kvasprintf_const+0x7a/0x90
>     [<ffffffff8c3b5481>] kobject_set_name_vargs+0x21/0x90
>     [<ffffffff8c4fbdd7>] dev_set_name+0x47/0x50
>     [<ffffffffc07819e5>] memstick_check+0x95/0x33c [memstick]
>     [<ffffffff8c09c893>] process_one_work+0x1f3/0x4b0
>     [<ffffffff8c09cb98>] worker_thread+0x48/0x4e0
>     [<ffffffff8c0a2b79>] kthread+0xc9/0xe0
>     [<ffffffff8c6dab5f>] ret_from_fork+0x1f/0x40
>     [<ffffffffffffffff>] 0xffffffffffffffff
>=20
> Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
> ---
>  kernel/module.c | 1 +
>  1 file changed, 1 insertion(+)

Reviewed-by: Aaron Tomlin <atomlin@redhat.com>

--=20
Aaron Tomlin

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