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From: Alistair Popple <apopple@nvidia.com>
To: Colin King <colin.king@canonical.com>
Cc: Ben Skeggs <bskeggs@redhat.com>, David Airlie <airlied@linux.ie>,
	Daniel Vetter <daniel@ffwll.ch>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Andrew Morton <akpm@linux-foundation.org>,
	<dri-devel@lists.freedesktop.org>,
	<nouveau@lists.freedesktop.org>,
	<kernel-janitors@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH][next] nouveau/svm: Fix missing failure check on call to make_device_exclusive_range
Date: Thu, 27 May 2021 10:30:34 +1000	[thread overview]
Message-ID: <2050838.rP6W8OkBfs@nvdebian> (raw)
In-Reply-To: <20210526140459.3749959-1-colin.king@canonical.com>

On Thursday, 27 May 2021 12:04:59 AM AEST Colin King wrote:
> The call to make_device_exclusive_range can potentially fail leaving
> pointer page not initialized that leads to an uninitialized pointer
> read issue. Fix this by adding a check to see if the call failed and
> returning the error code.
> 
> Addresses-Coverity: ("Uninitialized pointer read")
> Fixes: c620bba9828c ("nouveau/svm: implement atomic SVM access")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_svm.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c
> b/drivers/gpu/drm/nouveau/nouveau_svm.c index 84726a89e665..b913b4907088
> 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_svm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
> @@ -609,8 +609,10 @@ static int nouveau_atomic_range_fault(struct
> nouveau_svmm *svmm,
> 
>                 notifier_seq = mmu_interval_read_begin(&notifier->notifier);
> mmap_read_lock(mm);
> -               make_device_exclusive_range(mm, start, start + PAGE_SIZE,
> -                                           &page, drm->dev);
> +               ret = make_device_exclusive_range(mm, start, start +
> PAGE_SIZE, +                                                 &page,
> drm->dev); +               if (ret < 0)
> +                       goto out;

Thanks for spotting, this is fixing get_user_pages() inside 
make_device_exclusive_range() returning an error. However the check needs to 
happen after dropping mmap_lock below:

>                 mmap_read_unlock(mm);
>                 if (!page) {
>                         ret = -EINVAL;
> --
> 2.31.1





WARNING: multiple messages have this Message-ID (diff)
From: Alistair Popple <apopple@nvidia.com>
To: Colin King <colin.king@canonical.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
	David Airlie <airlied@linux.ie>,
	nouveau@lists.freedesktop.org, kernel-janitors@vger.kernel.org,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	Ben Skeggs <bskeggs@redhat.com>, Daniel Vetter <daniel@ffwll.ch>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [Nouveau] [PATCH][next] nouveau/svm: Fix missing failure check on call to make_device_exclusive_range
Date: Thu, 27 May 2021 10:30:34 +1000	[thread overview]
Message-ID: <2050838.rP6W8OkBfs@nvdebian> (raw)
In-Reply-To: <20210526140459.3749959-1-colin.king@canonical.com>

On Thursday, 27 May 2021 12:04:59 AM AEST Colin King wrote:
> The call to make_device_exclusive_range can potentially fail leaving
> pointer page not initialized that leads to an uninitialized pointer
> read issue. Fix this by adding a check to see if the call failed and
> returning the error code.
> 
> Addresses-Coverity: ("Uninitialized pointer read")
> Fixes: c620bba9828c ("nouveau/svm: implement atomic SVM access")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_svm.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c
> b/drivers/gpu/drm/nouveau/nouveau_svm.c index 84726a89e665..b913b4907088
> 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_svm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
> @@ -609,8 +609,10 @@ static int nouveau_atomic_range_fault(struct
> nouveau_svmm *svmm,
> 
>                 notifier_seq = mmu_interval_read_begin(&notifier->notifier);
> mmap_read_lock(mm);
> -               make_device_exclusive_range(mm, start, start + PAGE_SIZE,
> -                                           &page, drm->dev);
> +               ret = make_device_exclusive_range(mm, start, start +
> PAGE_SIZE, +                                                 &page,
> drm->dev); +               if (ret < 0)
> +                       goto out;

Thanks for spotting, this is fixing get_user_pages() inside 
make_device_exclusive_range() returning an error. However the check needs to 
happen after dropping mmap_lock below:

>                 mmap_read_unlock(mm);
>                 if (!page) {
>                         ret = -EINVAL;
> --
> 2.31.1




_______________________________________________
Nouveau mailing list
Nouveau@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/nouveau

WARNING: multiple messages have this Message-ID (diff)
From: Alistair Popple <apopple@nvidia.com>
To: Colin King <colin.king@canonical.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
	David Airlie <airlied@linux.ie>,
	nouveau@lists.freedesktop.org, kernel-janitors@vger.kernel.org,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	Ben Skeggs <bskeggs@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH][next] nouveau/svm: Fix missing failure check on call to make_device_exclusive_range
Date: Thu, 27 May 2021 10:30:34 +1000	[thread overview]
Message-ID: <2050838.rP6W8OkBfs@nvdebian> (raw)
In-Reply-To: <20210526140459.3749959-1-colin.king@canonical.com>

On Thursday, 27 May 2021 12:04:59 AM AEST Colin King wrote:
> The call to make_device_exclusive_range can potentially fail leaving
> pointer page not initialized that leads to an uninitialized pointer
> read issue. Fix this by adding a check to see if the call failed and
> returning the error code.
> 
> Addresses-Coverity: ("Uninitialized pointer read")
> Fixes: c620bba9828c ("nouveau/svm: implement atomic SVM access")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_svm.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c
> b/drivers/gpu/drm/nouveau/nouveau_svm.c index 84726a89e665..b913b4907088
> 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_svm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_svm.c
> @@ -609,8 +609,10 @@ static int nouveau_atomic_range_fault(struct
> nouveau_svmm *svmm,
> 
>                 notifier_seq = mmu_interval_read_begin(&notifier->notifier);
> mmap_read_lock(mm);
> -               make_device_exclusive_range(mm, start, start + PAGE_SIZE,
> -                                           &page, drm->dev);
> +               ret = make_device_exclusive_range(mm, start, start +
> PAGE_SIZE, +                                                 &page,
> drm->dev); +               if (ret < 0)
> +                       goto out;

Thanks for spotting, this is fixing get_user_pages() inside 
make_device_exclusive_range() returning an error. However the check needs to 
happen after dropping mmap_lock below:

>                 mmap_read_unlock(mm);
>                 if (!page) {
>                         ret = -EINVAL;
> --
> 2.31.1





  reply	other threads:[~2021-05-27  0:30 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-26 14:04 [PATCH][next] nouveau/svm: Fix missing failure check on call to make_device_exclusive_range Colin King
2021-05-26 14:04 ` [Nouveau] " Colin King
2021-05-27  0:30 ` Alistair Popple [this message]
2021-05-27  0:30   ` Alistair Popple
2021-05-27  0:30   ` [Nouveau] " Alistair Popple

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