From: "Gustavo A. R. Silva" <gustavo@embeddedor.com> To: Len Baker <len.baker@gmx.com>, Daniel Mack <daniel@zonque.org>, Haojian Zhuang <haojian.zhuang@gmail.com>, Robert Jarzmik <robert.jarzmik@free.fr>, Vinod Koul <vkoul@kernel.org> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>, Kees Cook <keescook@chromium.org>, linux-arm-kernel@lists.infradead.org, dmaengine@vger.kernel.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] dmaengine: pxa_dma: Prefer struct_size over open coded arithmetic Date: Mon, 20 Sep 2021 19:00:58 -0500 [thread overview] Message-ID: <e7e103f3-74eb-9cf4-a150-e2333d4f2ace@embeddedor.com> (raw) In-Reply-To: <20210918104055.8444-1-len.baker@gmx.com> On 9/18/21 05:40, Len Baker wrote: > As noted in the "Deprecated Interfaces, Language Features, Attributes, > and Conventions" documentation [1], size calculations (especially > multiplication) should not be performed in memory allocator (or similar) > function arguments due to the risk of them overflowing. This could lead > to values wrapping around and a smaller allocation being made than the > caller was expecting. Using those allocations could lead to linear > overflows of heap memory and other misbehaviors. > > So, use the struct_size() helper to do the arithmetic instead of the > argument "size + count * size" in the kzalloc() function. > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments > > Signed-off-by: Len Baker <len.baker@gmx.com> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> > --- > drivers/dma/pxa_dma.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c > index 4a2a796e348c..52d04641e361 100644 > --- a/drivers/dma/pxa_dma.c > +++ b/drivers/dma/pxa_dma.c > @@ -742,8 +742,7 @@ pxad_alloc_desc(struct pxad_chan *chan, unsigned int nb_hw_desc) > dma_addr_t dma; > int i; > > - sw_desc = kzalloc(sizeof(*sw_desc) + > - nb_hw_desc * sizeof(struct pxad_desc_hw *), > + sw_desc = kzalloc(struct_size(sw_desc, hw_desc, nb_hw_desc), > GFP_NOWAIT); > if (!sw_desc) > return NULL; > -- > 2.25.1 >
WARNING: multiple messages have this Message-ID (diff)
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com> To: Len Baker <len.baker@gmx.com>, Daniel Mack <daniel@zonque.org>, Haojian Zhuang <haojian.zhuang@gmail.com>, Robert Jarzmik <robert.jarzmik@free.fr>, Vinod Koul <vkoul@kernel.org> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>, Kees Cook <keescook@chromium.org>, linux-arm-kernel@lists.infradead.org, dmaengine@vger.kernel.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] dmaengine: pxa_dma: Prefer struct_size over open coded arithmetic Date: Mon, 20 Sep 2021 19:00:58 -0500 [thread overview] Message-ID: <e7e103f3-74eb-9cf4-a150-e2333d4f2ace@embeddedor.com> (raw) In-Reply-To: <20210918104055.8444-1-len.baker@gmx.com> On 9/18/21 05:40, Len Baker wrote: > As noted in the "Deprecated Interfaces, Language Features, Attributes, > and Conventions" documentation [1], size calculations (especially > multiplication) should not be performed in memory allocator (or similar) > function arguments due to the risk of them overflowing. This could lead > to values wrapping around and a smaller allocation being made than the > caller was expecting. Using those allocations could lead to linear > overflows of heap memory and other misbehaviors. > > So, use the struct_size() helper to do the arithmetic instead of the > argument "size + count * size" in the kzalloc() function. > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments > > Signed-off-by: Len Baker <len.baker@gmx.com> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> > --- > drivers/dma/pxa_dma.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c > index 4a2a796e348c..52d04641e361 100644 > --- a/drivers/dma/pxa_dma.c > +++ b/drivers/dma/pxa_dma.c > @@ -742,8 +742,7 @@ pxad_alloc_desc(struct pxad_chan *chan, unsigned int nb_hw_desc) > dma_addr_t dma; > int i; > > - sw_desc = kzalloc(sizeof(*sw_desc) + > - nb_hw_desc * sizeof(struct pxad_desc_hw *), > + sw_desc = kzalloc(struct_size(sw_desc, hw_desc, nb_hw_desc), > GFP_NOWAIT); > if (!sw_desc) > return NULL; > -- > 2.25.1 > _______________________________________________ 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:[~2021-09-21 0:20 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-09-18 10:40 [PATCH] dmaengine: pxa_dma: Prefer struct_size over open coded arithmetic Len Baker 2021-09-18 10:40 ` Len Baker 2021-09-21 0:00 ` Gustavo A. R. Silva [this message] 2021-09-21 0:00 ` Gustavo A. R. Silva 2021-10-20 23:32 ` Gustavo A. R. Silva 2021-10-20 23:32 ` Gustavo A. R. Silva
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