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([2a02:810d:4b3f:ee94:abf:b8ff:feee:998b]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-422f5f33bdasm164871085e9.8.2024.06.17.08.55.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 17 Jun 2024 08:55:35 -0700 (PDT) Message-ID: Date: Mon, 17 Jun 2024 17:55:33 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] drm/nouveau: Use kmemdup_array() instead of kmemdup() To: Dan Carpenter Cc: Lyude Paul , David Airlie , Daniel Vetter , dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Karol Herbst References: Content-Language: en-US From: Danilo Krummrich Organization: RedHat In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 6/17/24 11:33, Dan Carpenter wrote: > Use kmemdup_array() because we're allocating an array. > > The main difference between kmemdup() and kmemdup_array() is that the > kmemdup_array() function has integer overflow checking built it. The > "args->in_sync.count" variable is a u32 so integer overflows would only > be a concern on 32bit systems. Fortunately, however, the u_memcpya() > function has integer overflow checking which means that it is not an > issue. > > Still using kmemdup_array() is more appropriate and makes auditing the > code easier. Indeed, we shouldn't rely on the previous check here, good catch. > > Signed-off-by: Dan Carpenter > --- > drivers/gpu/drm/nouveau/nouveau_sched.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/drivers/gpu/drm/nouveau/nouveau_sched.c b/drivers/gpu/drm/nouveau/nouveau_sched.c > index 32fa2e273965..53d8b0584a56 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_sched.c > +++ b/drivers/gpu/drm/nouveau/nouveau_sched.c > @@ -45,10 +45,10 @@ nouveau_job_init(struct nouveau_job *job, > if (job->sync) > return -EINVAL; > > - job->in_sync.data = kmemdup(args->in_sync.s, > - sizeof(*args->in_sync.s) * > - args->in_sync.count, > - GFP_KERNEL); > + job->in_sync.data = kmemdup_array(args->in_sync.s, > + args->in_sync.count, > + sizeof(*args->in_sync.s), > + GFP_KERNEL); > if (!job->in_sync.data) > return -ENOMEM; Not sure if this is what we want for kmemdup_array(). It just saturates the size. This doesn't prevent accessing the array out of bounds later on. I mean, it's rather unlikely to get such a huge amount of physically contiguous memory anyways, but wouldn't it be cleaner to let kmemdup_array() return ERR_PTR(-EOVERFLOW) on overflow, just like memdup_array_user()[1]? AFAICS, there's just two users of kmemdup_array(), hence it should be an easy change. :-) [1] https://elixir.bootlin.com/linux/latest/source/include/linux/string.h#L30 > } > @@ -60,10 +60,10 @@ nouveau_job_init(struct nouveau_job *job, > goto err_free_in_sync; > } > > - job->out_sync.data = kmemdup(args->out_sync.s, > - sizeof(*args->out_sync.s) * > - args->out_sync.count, > - GFP_KERNEL); > + job->out_sync.data = kmemdup_array(args->out_sync.s, > + args->out_sync.count, > + sizeof(*args->out_sync.s), > + GFP_KERNEL); > if (!job->out_sync.data) { > ret = -ENOMEM; > goto err_free_in_sync;