From: Steven Price <steven.price@arm.com> To: Kangjie Lu <kjlu@umn.edu> Cc: Heiko Stuebner <heiko@sntech.de>, Jacob chen <jacob2.chen@rock-chips.com>, linux-kernel@vger.kernel.org, linux-rockchip@lists.infradead.org, pakki001@umn.edu, Mauro Carvalho Chehab <mchehab@kernel.org>, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org Subject: Re: [PATCH v2] media: rga: fix NULL pointer dereferences and a memory leak Date: Wed, 13 Mar 2019 13:35:51 +0000 [thread overview] Message-ID: <ff11d704-489f-836e-6c9d-1b2fb5e963b6@arm.com> (raw) In-Reply-To: <20190312065824.19646-1-kjlu@umn.edu> On 12/03/2019 06:58, Kangjie Lu wrote: > In case __get_free_pages fails, the fix releases resources and > return -ENOMEM to avoid NULL pointer dereferences. > > Also, the fix frees pages when video_register_device fails to > avoid a memory leak. > > Signed-off-by: Kangjie Lu <kjlu@umn.edu> > --- > drivers/media/platform/rockchip/rga/rga.c | 15 ++++++++++++++- > 1 file changed, 14 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/platform/rockchip/rga/rga.c b/drivers/media/platform/rockchip/rga/rga.c > index 5c653287185f..307b7ab0ab64 100644 > --- a/drivers/media/platform/rockchip/rga/rga.c > +++ b/drivers/media/platform/rockchip/rga/rga.c > @@ -892,8 +892,17 @@ static int rga_probe(struct platform_device *pdev) > > rga->src_mmu_pages = > (unsigned int *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 3); > + if (!rga->src_mmu_pages) { > + ret = -ENOMEM; > + goto rel_vdev; > + } > + > rga->dst_mmu_pages = > (unsigned int *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 3); > + if (!rga->dst_mmu_pages) { > + ret = -ENOMEM; > + goto free_dst_pages; > + } > > def_frame.stride = (def_frame.width * def_frame.fmt->depth) >> 3; > def_frame.size = def_frame.stride * def_frame.height; > @@ -901,7 +910,7 @@ static int rga_probe(struct platform_device *pdev) > ret = video_register_device(vfd, VFL_TYPE_GRABBER, -1); > if (ret) { > v4l2_err(&rga->v4l2_dev, "Failed to register video device\n"); > - goto rel_vdev; > + goto free_pages; > } > > v4l2_info(&rga->v4l2_dev, "Registered %s as /dev/%s\n", > @@ -909,6 +918,10 @@ static int rga_probe(struct platform_device *pdev) > > return 0; > > +free_pages: > + free_pages((unsigned long)rga->src_mmu_pages, 3); > +free_dst_pages: > + free_pages((unsigned long)rga->dst_mmu_pages, 3); > rel_vdev: > video_device_release(vfd); > unreg_video_dev: That looks good. However looking into the error path more closely it appears that this was already rather broken. Here's the original: > rel_vdev: > video_device_release(vfd); > unreg_video_dev: > video_unregister_device(rga->vfd); > unreg_v4l2_dev: > v4l2_device_unregister(&rga->v4l2_dev); > err_put_clk: > pm_runtime_disable(rga->dev); video_device_release() is simply a call to kfree(), but video_unregister_device will then be called with the same pointer (rga->vfd is set to vfd further up). Which will then cause a use-after-free on the pointer. It might be a good idea to test this error path, for example make the video_register_device() call always fail and run with memory debuggers enabled (e.g. CONFIG_KASAN or CONFIG_DEBUG_KMEM_LEAK). Steve
WARNING: multiple messages have this Message-ID (diff)
From: Steven Price <steven.price@arm.com> To: Kangjie Lu <kjlu@umn.edu> Cc: Heiko Stuebner <heiko@sntech.de>, Jacob chen <jacob2.chen@rock-chips.com>, linux-kernel@vger.kernel.org, linux-rockchip@lists.infradead.org, pakki001@umn.edu, Mauro Carvalho Chehab <mchehab@kernel.org>, linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org Subject: Re: [PATCH v2] media: rga: fix NULL pointer dereferences and a memory leak Date: Wed, 13 Mar 2019 13:35:51 +0000 [thread overview] Message-ID: <ff11d704-489f-836e-6c9d-1b2fb5e963b6@arm.com> (raw) In-Reply-To: <20190312065824.19646-1-kjlu@umn.edu> On 12/03/2019 06:58, Kangjie Lu wrote: > In case __get_free_pages fails, the fix releases resources and > return -ENOMEM to avoid NULL pointer dereferences. > > Also, the fix frees pages when video_register_device fails to > avoid a memory leak. > > Signed-off-by: Kangjie Lu <kjlu@umn.edu> > --- > drivers/media/platform/rockchip/rga/rga.c | 15 ++++++++++++++- > 1 file changed, 14 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/platform/rockchip/rga/rga.c b/drivers/media/platform/rockchip/rga/rga.c > index 5c653287185f..307b7ab0ab64 100644 > --- a/drivers/media/platform/rockchip/rga/rga.c > +++ b/drivers/media/platform/rockchip/rga/rga.c > @@ -892,8 +892,17 @@ static int rga_probe(struct platform_device *pdev) > > rga->src_mmu_pages = > (unsigned int *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 3); > + if (!rga->src_mmu_pages) { > + ret = -ENOMEM; > + goto rel_vdev; > + } > + > rga->dst_mmu_pages = > (unsigned int *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 3); > + if (!rga->dst_mmu_pages) { > + ret = -ENOMEM; > + goto free_dst_pages; > + } > > def_frame.stride = (def_frame.width * def_frame.fmt->depth) >> 3; > def_frame.size = def_frame.stride * def_frame.height; > @@ -901,7 +910,7 @@ static int rga_probe(struct platform_device *pdev) > ret = video_register_device(vfd, VFL_TYPE_GRABBER, -1); > if (ret) { > v4l2_err(&rga->v4l2_dev, "Failed to register video device\n"); > - goto rel_vdev; > + goto free_pages; > } > > v4l2_info(&rga->v4l2_dev, "Registered %s as /dev/%s\n", > @@ -909,6 +918,10 @@ static int rga_probe(struct platform_device *pdev) > > return 0; > > +free_pages: > + free_pages((unsigned long)rga->src_mmu_pages, 3); > +free_dst_pages: > + free_pages((unsigned long)rga->dst_mmu_pages, 3); > rel_vdev: > video_device_release(vfd); > unreg_video_dev: That looks good. However looking into the error path more closely it appears that this was already rather broken. Here's the original: > rel_vdev: > video_device_release(vfd); > unreg_video_dev: > video_unregister_device(rga->vfd); > unreg_v4l2_dev: > v4l2_device_unregister(&rga->v4l2_dev); > err_put_clk: > pm_runtime_disable(rga->dev); video_device_release() is simply a call to kfree(), but video_unregister_device will then be called with the same pointer (rga->vfd is set to vfd further up). Which will then cause a use-after-free on the pointer. It might be a good idea to test this error path, for example make the video_register_device() call always fail and run with memory debuggers enabled (e.g. CONFIG_KASAN or CONFIG_DEBUG_KMEM_LEAK). Steve _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-03-13 13:35 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-03-09 6:35 [PATCH] media: rga: fix NULL pointer dereferences Kangjie Lu 2019-03-09 6:35 ` Kangjie Lu 2019-03-11 13:15 ` Steven Price 2019-03-11 13:15 ` Steven Price 2019-03-12 6:58 ` [PATCH v2] media: rga: fix NULL pointer dereferences and a memory leak Kangjie Lu 2019-03-12 6:58 ` Kangjie Lu 2019-03-13 13:35 ` Steven Price [this message] 2019-03-13 13:35 ` Steven Price 2019-03-14 5:03 ` [PATCH v3] media: rga: fix NULL pointer dereferences, use-after-free, " Kangjie Lu 2019-03-14 5:03 ` Kangjie Lu 2019-03-14 10:30 ` Steven Price 2019-03-14 10:30 ` Steven Price 2019-03-28 14:47 ` Hans Verkuil 2019-03-28 14:47 ` Hans Verkuil 2019-03-28 15:00 ` Kangjie Lu 2019-03-28 15:00 ` Kangjie Lu
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