Fix mmap_base entropy for >31 bits.
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- v1 Latest2 patches 4 repliesIn review
Patches in v1 No applies recorded yet
| # | Subject and files | Size | Replies | Applied |
|---|---|---|---|---|
| 1/2 | drivers: char: random: Add get_random_long().drivers/ include/ | +23 | 0 replies | |
| 2/2 | use get_random_long().arch/ arch/ arch/ +5 more | +14 | 1 reply |
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None of the 2 patches has a Reviewed-by or Acked-by of their own; the series has one for all of them.
| Patch | Kees Cook |
|---|---|
| Series | A-b |
| 1/2 | |
| 2/2 |
Trailers given in replies are filled; those carried in the patches from earlier versions are outlined with dashes.
Cover letter [PATCH 0/2] Fix mmap_base entropy for >31 bits.
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(-)
Signature · 1 line
2.7.0.rc3.207.g0ac5344