On Fri, 2023-10-20 at 20:30:29 UTC, Linus Walleij wrote: > 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 > Reviewed-by: Nicolas Pitre <nico@xxxxxxxxxxx> > Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx> Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next, thanks. Miquel
