On Tue, Aug 11, 2020 at 10:57:02AM +0300, Dan Carpenter wrote:
> On Mon, Aug 10, 2020 at 08:41:14PM +0200, Marion & Christophe JAILLET wrote:
> >
> > Le 10/08/2020 à 17:42, Dan Carpenter a écrit :
> > > On Sun, Aug 09, 2020 at 10:34:06PM +0200, Christophe JAILLET wrote:
> > > > When '*sgt' is allocated, we must allocated 'sizeof(**sgt)' bytes instead
> > > > of 'sizeof(*sg)'. 'sg' (i.e. struct scatterlist) is smaller than
> > > > 'sgt' (i.e struct sg_table), so this could lead to memory corruption.
> > > The sizeof(*sg) is bigger than sizeof(**sgt) so this wastes memory but
> > > it won't lead to corruption.
> > >
> > > 11 struct scatterlist {
> > > 12 unsigned long page_link;
> > > 13 unsigned int offset;
> > > 14 unsigned int length;
> > > 15 dma_addr_t dma_address;
> > > 16 #ifdef CONFIG_NEED_SG_DMA_LENGTH
> > > 17 unsigned int dma_length;
> > > 18 #endif
> > > 19 };
> > >
> > > 42 struct sg_table {
> > > 43 struct scatterlist *sgl; /* the list */
> > > 44 unsigned int nents; /* number of mapped entries */
> > > 45 unsigned int orig_nents; /* original size of list */
> > > 46 };
> > >
> > > regards,
> > > dan carpenter
> >
> >
> > My bad. I read 'struct scatterlist sgl' (without the *)
> > Thanks for the follow-up, Dan.
> >
> > Doesn't smatch catch such mismatch?
> > (I've not run smatch for a while, so it is maybe reported)
>
> That's why I was investigating it, because Smatch didn't catch it.
>
> Smatch would have warned if it led to memory corruption. Smatch also
> tries to detect struct mismatches as a separate check but for some
> reason it missed it. I'm not totally sure why yet. I suspect that it's
> a complicated internal reason where Sparse is the sizeof to a normal
s/is/changes/
> number... It's a known issue and hard to fix.
regards,
dan carpenter
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