UPSTREAM: fs/binfmt_elf.c: fix bug in loading of PIE binaries
With CONFIG_ARCH_BINFMT_ELF_RANDOMIZE_PIE enabled, and a normal top-down
address allocation strategy, load_elf_binary() will attempt to map a PIE
binary into an address range immediately below mm->mmap_base.
Unfortunately, load_elf_ binary() does not take account of the need to
allocate sufficient space for the entire binary which means that, while
the first PT_LOAD segment is mapped below mm->mmap_base, the subsequent
PT_LOAD segment(s) end up being mapped above mm->mmap_base into the are
that is supposed to be the "gap" between the stack and the binary.
Since the size of the "gap" on x86_64 is only guaranteed to be 128MB this
means that binaries with large data segments > 128MB can end up mapping
part of their data segment over their stack resulting in corruption of the
stack (and the data segment once the binary starts to run).
Any PIE binary with a data segment > 128MB is vulnerable to this although
address randomization means that the actual gap between the stack and the
end of the binary is normally greater than 128MB. The larger the data
segment of the binary the higher the probability of failure.
Fix this by calculating the total size of the binary in the same way as
load_elf_interp().
Signed-off-by: Michael Davidson <md@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Kees Cook <keescook@chromium.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit a87938b2e246b81b4fb713edb371a9fa3c5c3c86)
Signed-off-by: Nicolas Boichat <drinkcat@google.com>
BUG=b:33398361, chromium:769657
TEST=Run CTS CtsAslrMallocTestCases module
Change-Id: I19fb75f591778fb39e64d99d368b4ffdfb70f63d
Reviewed-on: https://chromium-review.googlesource.com/420729
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Mattias Nissler <mnissler@chromium.org>
(cherry picked from commit ff9ef827ff5edfd0d6d0a970e39a6ca127676c25)
Reviewed-on: https://chromium-review.googlesource.com/690694
Commit-Ready: Guenter Roeck <groeck@chromium.org>
Tested-by: Guenter Roeck <groeck@chromium.org>
Reviewed-by: Dylan Reid <dgreid@chromium.org>
(cherry picked from commit 07be10425fd4764b38a51ae2679e9c4fdc89baec)
Reviewed-on: https://chromium-review.googlesource.com/692558
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Commit-Queue: Guenter Roeck <groeck@chromium.org>
1 file changed
