Re: [PATCH v2] mtdoops: Fix the size of the header read buffer.

From: Miquel Raynal
Date: Mon Feb 07 2022 - 10:44:39 EST


Hi Jean-Marc,

It looks like you changed the title when answering to my question, I
thought this was a v2 and could not find it in patchwork. That is
because the v2 does not actually exist?

jmeurin@xxxxxxxxxx wrote on Thu, 3 Feb 2022 17:53:47
-0800:

> On Mon, Jan 31, 2022 at 2:00 AM Miquel Raynal <miquel.raynal@xxxxxxxxxxx> wrote:
> >
> > Hi Jean-Marc,
> >
> > jmeurin@xxxxxxxxxx wrote on Fri, 28 Jan 2022 14:01:56 -0800:
> >
> > > The read buffer size depends on the MTDOOPS_HEADER_SIZE.
> > >
> > > Tested: Changed the header size, it doesn't panic, header is still
> > > read/written correctly.
> >
> > On what Linux kernel version are you? It looks like we don't share the
> > same code base, are we?
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/mtd/mtdoops.c?h=v5.17-rc2
> has that bug. If you try to increase the MTDOOPS_HEADER_SIZE,
> find_next_position() will try to do an mtd_read() of
> MTDOOPS_HEADER_SIZE bytes in a count buffer that is fixed to only 8
> bytes.

I might have checked another function then. Indeed the fix looks legit.

Can you please send a v2 with:
- Your two patches in the same series (formatted with git-format-patch
to get the dependency/order right)
- In the other commit, drop the reference pointing to (I believe) a
commit hash that is local to your tree only.
- Use the right prefix ("mtd: mtdoops:").

And we should be good.

>
> Thanks,
>
> Jean-Marc
>
> >
> > >
> > > Signed-off-by: Jean-Marc Eurin <jmeurin@xxxxxxxxxx>
> > > ---
> > > drivers/mtd/mtdoops.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/mtd/mtdoops.c b/drivers/mtd/mtdoops.c
> > > index 227df24387df..09a26747f490 100644
> > > --- a/drivers/mtd/mtdoops.c
> > > +++ b/drivers/mtd/mtdoops.c
> > > @@ -223,7 +223,7 @@ static void find_next_position(struct mtdoops_context *cxt)
> > > {
> > > struct mtd_info *mtd = cxt->mtd;
> > > int ret, page, maxpos = 0;
> > > - u32 count[2], maxcount = 0xffffffff;
> > > + u32 count[MTDOOPS_HEADER_SIZE/sizeof(u32)], maxcount = 0xffffffff;
> > > size_t retlen;
> > >
> > > for (page = 0; page < cxt->oops_pages; page++) {
> >
> >
> > Thanks,
> > Miquèl


Thanks,
Miquèl