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Wed, 4 Mar 2020 02:41:18 -0600 Received: from fllv0040.itg.ti.com (10.64.41.20) by DLEE112.ent.ti.com (157.170.170.23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1847.3 via Frontend Transport; Wed, 4 Mar 2020 02:41:18 -0600 Received: from [192.168.2.6] (ileax41-snat.itg.ti.com [10.172.224.153]) by fllv0040.itg.ti.com (8.15.2/8.15.2) with ESMTP id 0248fGQt038530; Wed, 4 Mar 2020 02:41:17 -0600 Subject: Re: [Patch] media: ti-vpe: cal: fix a kernel oops when unloading module From: Tomi Valkeinen To: Benoit Parrot , Hans Verkuil CC: , , , References: <20200303172629.21339-1-bparrot@ti.com> <4010c13f-6a32-f3c3-5b6d-62a4e3782c64@ti.com> Message-ID: Date: Wed, 4 Mar 2020 10:41:16 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <4010c13f-6a32-f3c3-5b6d-62a4e3782c64@ti.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On 04/03/2020 10:40, Tomi Valkeinen wrote: > On 03/03/2020 19:26, Benoit Parrot wrote: >> After the switch to use v4l2_async_notifier_add_subdev() and >> v4l2_async_notifier_cleanup(), unloading the ti_cal module would casue a >> kernel oops. >> >> This was root cause to the fact that v4l2_async_notifier_cleanup() tries >> to kfree the asd pointer passed into v4l2_async_notifier_add_subdev(). >> >> In our case the asd reference was from a statically allocated struct. >> So in effect v4l2_async_notifier_cleanup() was trying to free a pointer >> that was not kalloc. >> >> So here we switch to using a kzalloc struct instead of a static one. >> >> Fixes: d079f94c9046 ("media: platform: Switch to v4l2_async_notifier_add_subdev") >> >> Cc: stable@vger.kernel.org >> Signed-off-by: Benoit Parrot >> --- >>   drivers/media/platform/ti-vpe/cal.c | 7 ++++--- >>   1 file changed, 4 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/media/platform/ti-vpe/cal.c b/drivers/media/platform/ti-vpe/cal.c >> index 6d4cbb8782ed..18fe2cb9dd17 100644 >> --- a/drivers/media/platform/ti-vpe/cal.c >> +++ b/drivers/media/platform/ti-vpe/cal.c >> @@ -372,8 +372,6 @@ struct cal_ctx { >>       struct v4l2_subdev    *sensor; >>       struct v4l2_fwnode_endpoint    endpoint; >> -    struct v4l2_async_subdev asd; >> - >>       struct v4l2_fh        fh; >>       struct cal_dev        *dev; >>       struct cc_data        *cc; >> @@ -2032,7 +2030,6 @@ static int of_cal_create_instance(struct cal_ctx *ctx, int inst) >>       parent = pdev->dev.of_node; >> -    asd = &ctx->asd; >>       endpoint = &ctx->endpoint; >>       ep_node = NULL; >> @@ -2040,6 +2037,10 @@ static int of_cal_create_instance(struct cal_ctx *ctx, int inst) >>       sensor_node = NULL; >>       ret = -EINVAL; >> +    asd = kzalloc(sizeof(*asd), GFP_KERNEL); >> +    if (!asd) >> +        goto cleanup_exit; >> + >>       ctx_dbg(3, ctx, "Scanning Port node for csi2 port: %d\n", inst); >>       for (index = 0; index < CAL_NUM_CSI2_PORTS; index++) { >>           port = of_get_next_port(parent, port); >> > > Thanks, this fixes the crash for me. > > It does look a bit odd that something is allocated with kzalloc, and then it's freed somewhere > inside v4l2_async_notifier_cleanup, though. But if that's how it supposed to be used, looks fine to me. Well, sent that a few seconds too early... With this patch, I see kmemleaks. Tomi -- Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki