Hi Linus, linus.walleij@xxxxxxxxxx wrote on Mon, 23 Oct 2023 10:35:24 +0200: > On Mon, Oct 23, 2023 at 10:25 AM Miquel Raynal > <miquel.raynal@xxxxxxxxxxx> wrote: > > > linus.walleij@xxxxxxxxxx wrote on Fri, 20 Oct 2023 22:30:29 +0200: > > > > > Currently the offset into the device when looking for OTP > > > bits can go outside of the address of the MTD NOR devices, > > > and if that memory isn't readable, bad things happen > > > on the IXP4xx (added prints that illustrate the problem before > > > the crash): > > > > > > cfi_intelext_otp_walk walk OTP on chip 0 start at reg_prot_offset 0x00000100 > > > ixp4xx_copy_from copy from 0x00000100 to 0xc880dd78 > > > cfi_intelext_otp_walk walk OTP on chip 0 start at reg_prot_offset 0x12000000 > > > ixp4xx_copy_from copy from 0x12000000 to 0xc880dd78 > > > 8<--- cut here --- > > > Unable to handle kernel paging request at virtual address db000000 > > > [db000000] *pgd=00000000 > > > (...) > > > > > > This happens in this case because the IXP4xx is big endian and > > > the 32- and 16-bit fields in the struct cfi_intelext_otpinfo are not > > > properly byteswapped. Compare to how the code in read_pri_intelext() > > > byteswaps the fields in struct cfi_pri_intelext. > > > > > > Adding a small byte swapping loop for the OTP in read_pri_intelext() > > > and the crash goes away. > > > > > > The problem went unnoticed for many years until I enabled > > > CONFIG_MTD_OTP on the IXP4xx as well, triggering the bug. > > > > > > Cc: stable@xxxxxxxxxxxxxxx > > > > Would you like to add a Fixes tag as well? Or is this skipped on > > purpose? > > Yes the actual commit predates existing git history... :/ > > Git blame looks like that: > > ^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 423) > ^1da177e4c3f4 (Linus Torvalds 2005-04-16 15:20:36 -0700 424) > /* Protection Register info */ > b359ed5184aeb (Jean-Philippe Brucker 2020-04-17 16:23:26 +0200 425) > if (extp->NumProtectionFields) > b359ed5184aeb (Jean-Philippe Brucker 2020-04-17 16:23:26 +0200 426) > extra_size += (extp->NumProtectionFields - 1) * > b359ed5184aeb (Jean-Philippe Brucker 2020-04-17 16:23:26 +0200 427) > sizeof(struct cfi_intelext_otpinfo); > > Jean-Philippe's patch is not the root cause AFAICT, but something > predating it, and predating git history. > > The fix easily applies to all maintained stable kernels. Ack. > > > Reviewed-by: Nicolas Pitre <nico@xxxxxxxxxxx> > > > Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx> > > > --- > > > ChangeLog v3->v4: > > > - Collected Nico's ACK. > > > - Stalled since june! Has this been missed? > > > > Our current organization relies on Vignesh to pick-up (or tell me to > > pick-up) cfi patches. But he is slightly less active these days, so if I > > don't get any feedback from him soon I will take it for the next merge > > window. > > > > Sorry for the delay anyway. > > No worries it's not like the patch is urgent. Haha, well, yes :) Thanks, Miquèl
