On Wed, Feb 24, 2016 at 12:40 PM, Daniel Cashman <[email protected]> wrote: > On 02/04/2016 02:29 PM, Kees Cook wrote: >> On Thu, Feb 4, 2016 at 2:06 PM, Daniel Cashman <[email protected]> wrote: >>> Upstream commit: d07e22597d1d355829b7b18ac19afa912cf758d1 added the >>> ability to choose from a range of values to use for entropy count in >>> generating the random offset to the mmap_base address. The >>> maximum value on this range was set to 32 bits for 64-bit x86 systems, >>> but this value could be increased further, requiring more than the 32 >>> bits of randomness provided by get_random_int(), as is already possible >>> for arm64. Add a new function: get_random_long() which more naturally >>> fits with the mmap usage of get_random_int() but operates exactly the >>> same as get_random_int(). >>> >>> Also, fix the shifting constant in mmap_rnd() to be an unsigned long so >>> that values greater than 31 bits generate an appropriate mask without >>> overflow. This is especially important on x86, as its shift instruction >>> uses a 5-bit mask for the shift operand, which meant that any value for >>> mmap_rnd_bits over 31 acts as a no-op and effectively disables mmap_base >>> randomization. >>> >>> Finally, replace calls to get_random_int() with get_random_long() where >>> appropriate. >>> >>> Daniel Cashman (2): >>> drivers: char: random: Add get_random_long(). >>> use get_random_long(). >>> >>> arch/arm/mm/mmap.c | 2 +- >>> arch/arm64/mm/mmap.c | 4 ++-- >>> arch/mips/mm/mmap.c | 4 ++-- >>> arch/powerpc/kernel/process.c | 4 ++-- >>> arch/powerpc/mm/mmap.c | 4 ++-- >>> arch/sparc/kernel/sys_sparc_64.c | 2 +- >>> arch/x86/mm/mmap.c | 6 +++--- >>> drivers/char/random.c | 22 ++++++++++++++++++++++ >>> fs/binfmt_elf.c | 2 +- >>> include/linux/random.h | 1 + >>> 10 files changed, 37 insertions(+), 14 deletions(-) >> >> Thanks for fixing this! >> >> Acked-by: Kees Cook <[email protected]> >> >> -Kees >> > > This has now been in linux-next for awhile. Could we please submit this > for the 4.5 rc window so that it fixes the issue in the final 4.5 > release? Sorry if this is a protocol breach, but I'm not sure what the > best way is for me to indicate that this is a "fix" that should go out > in the same release as the original feature.
Yes please! :) Andrew, can you push these for 4.5? Best to keep the feature from releasing broken. Thanks! -Kees -- Kees Cook Chrome OS & Brillo Security
