Hi Gustavo, "Gustavo A. R. Silva" <gust...@embeddedor.com> wrote on Fri, 12 Feb 2021 08:45:33 -0600:
> On 2/12/21 08:12, Miquel Raynal wrote: > > Hi Gustavo, > > > > "Gustavo A. R. Silva" <gustavo...@kernel.org> wrote on Fri, 12 Feb 2021 > > 04:40:22 -0600: > > > >> Cast &data to (char *) in order to avoid unintentionally accessing > >> the stack. > >> > >> Notice that data is of type u32, so any increment to &data > >> will be in the order of 4-byte chunks, and this piece of code > >> is actually intended to be a byte offset. > > > > I don't have the same reading. I don't say that Coverity report is > > wrong, but let's discuss this a bit further. > > > > Given that &data is of type u32 *, you say that "&data + shift" > > produces increments of 4-bytes, ie. we would access "&data + 4 * > > shift"? Because I don't think this is the case (again, I may be wrong). > > Yep; this is pointer arithmetic. If you have an object ptr of type u32 *: > > u32 *ptr; > > and let's say it points to address 100. If you increment it by one: > > ptr++ > > ptr will now point to address 104, not to 101. > > Now, if instead, you first cast ptr to 'char *' and increment it by 1, > then it will point to address 101. Yep, I got confused with the proper addition compared to dereferencing. Patch looks legitimate. Thanks, Miquèl
