On 02/04/2016 02:29 PM, Kees Cook wrote: > On Thu, Feb 4, 2016 at 2:06 PM, Daniel Cashman <dcash...@android.com> 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 <keesc...@chromium.org> > > -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. Thank You, Dan
