linux-stable.git/fs/binfmt_elf.c, branch v3.2.78

binfmt_elf: Don't clobber passed executable's file header

2015-11-27T12:48:24+00:00

commit b582ef5c53040c5feef4c96a8f9585b6831e2441 upstream.

Do not clobber the buffer space passed from `search_binary_handler' and
originally preloaded by `prepare_binprm' with the executable's file
header by overwriting it with its interpreter's file header.  Instead
keep the buffer space intact and directly use the data structure locally
allocated for the interpreter's file header, fixing a bug introduced in
2.1.14 with loadable module support (linux-mips.org commit beb11695
[Import of Linux/MIPS 2.1.14], predating kernel.org repo's history).
Adjust the amount of data read from the interpreter's file accordingly.

This was not an issue before loadable module support, because back then
`load_elf_binary' was executed only once for a given ELF executable,
whether the function succeeded or failed.

With loadable module support supported and enabled, upon a failure of
`load_elf_binary' -- which may for example be caused by architecture
code rejecting an executable due to a missing hardware feature requested
in the file header -- a module load is attempted and then the function
reexecuted by `search_binary_handler'.  With the executable's file
header replaced with its interpreter's file header the executable can
then be erroneously accepted in this subsequent attempt.

Signed-off-by: Maciej W. Rozycki 
Signed-off-by: Al Viro 
Signed-off-by: Ben Hutchings

fs/binfmt_elf.c:load_elf_binary(): return -EINVAL on zero-length mappings

2015-08-06T23:32:13+00:00

commit 2b1d3ae940acd11be44c6eced5873d47c2e00ffa upstream.

load_elf_binary() returns `retval', not `error'.

Fixes: a87938b2e246b81b4fb ("fs/binfmt_elf.c: fix bug in loading of PIE binaries")
Reported-by: James Hogan 
Cc: Michael Davidson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Ben Hutchings

fs/binfmt_elf.c: fix bug in loading of PIE binaries

2015-08-06T23:32:05+00:00

commit a87938b2e246b81b4fb713edb371a9fa3c5c3c86 upstream.

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 
Cc: Alexander Viro 
Cc: Jiri Kosina 
Cc: Kees Cook 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Ben Hutchings

x86, mm/ASLR: Fix stack randomization on 64-bit systems

2015-05-09T22:16:19+00:00

commit 4e7c22d447bb6d7e37bfe39ff658486ae78e8d77 upstream.

The issue is that the stack for processes is not properly randomized on
64 bit architectures due to an integer overflow.

The affected function is randomize_stack_top() in file
"fs/binfmt_elf.c":

  static unsigned long randomize_stack_top(unsigned long stack_top)
  {
           unsigned int random_variable = 0;

           if ((current->flags & PF_RANDOMIZE) &&
                   !(current->personality & ADDR_NO_RANDOMIZE)) {
                   random_variable = get_random_int() & STACK_RND_MASK;
                   random_variable <<= PAGE_SHIFT;
           }
           return PAGE_ALIGN(stack_top) + random_variable;
           return PAGE_ALIGN(stack_top) - random_variable;
  }

Note that, it declares the "random_variable" variable as "unsigned int".
Since the result of the shifting operation between STACK_RND_MASK (which
is 0x3fffff on x86_64, 22 bits) and PAGE_SHIFT (which is 12 on x86_64):

	  random_variable <<= PAGE_SHIFT;

then the two leftmost bits are dropped when storing the result in the
"random_variable". This variable shall be at least 34 bits long to hold
the (22+12) result.

These two dropped bits have an impact on the entropy of process stack.
Concretely, the total stack entropy is reduced by four: from 2^28 to
2^30 (One fourth of expected entropy).

This patch restores back the entropy by correcting the types involved
in the operations in the functions randomize_stack_top() and
stack_maxrandom_size().

The successful fix can be tested with:

  $ for i in `seq 1 10`; do cat /proc/self/maps | grep stack; done
  7ffeda566000-7ffeda587000 rw-p 00000000 00:00 0                          [stack]
  7fff5a332000-7fff5a353000 rw-p 00000000 00:00 0                          [stack]
  7ffcdb7a1000-7ffcdb7c2000 rw-p 00000000 00:00 0                          [stack]
  7ffd5e2c4000-7ffd5e2e5000 rw-p 00000000 00:00 0                          [stack]
  ...

Once corrected, the leading bytes should be between 7ffc and 7fff,
rather than always being 7fff.

Signed-off-by: Hector Marco-Gisbert 
Signed-off-by: Ismael Ripoll 
[ Rebased, fixed 80 char bugs, cleaned up commit message, added test example and CVE ]
Signed-off-by: Kees Cook 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Cc: Al Viro 
Fixes: CVE-2015-1593
Link: http://lkml.kernel.org/r/20150214173350.GA18393@www.outflux.net
Signed-off-by: Borislav Petkov 
Signed-off-by: Ben Hutchings

coredump: prevent double-free on an error path in core dumper

2012-10-17T02:49:05+00:00

commit f34f9d186df35e5c39163444c43b4fc6255e39c5 upstream.

In !CORE_DUMP_USE_REGSET case, if elf_note_info_init fails to allocate
memory for info->fields, it frees already allocated stuff and returns
error to its caller, fill_note_info.  Which in turn returns error to its
caller, elf_core_dump.  Which jumps to cleanup label and calls
free_note_info, which will happily try to free all info->fields again.
BOOM.

This is the fix.

Signed-off-by: Oleg Nesterov 
Signed-off-by: Denys Vlasenko 
Cc: Venu Byravarasu 
Signed-off-by: Andrew Morton 
Signed-off-by: Ben Hutchings

regset: Prevent null pointer reference on readonly regsets

2012-03-12T19:31:24+00:00

commit c8e252586f8d5de906385d8cf6385fee289a825e upstream.

The regset common infrastructure assumed that regsets would always
have .get and .set methods, but not necessarily .active methods.
Unfortunately people have since written regsets without .set methods.

Rather than putting in stub functions everywhere, handle regsets with
null .get or .set methods explicitly.

Signed-off-by: H. Peter Anvin 
Reviewed-by: Oleg Nesterov 
Acked-by: Roland McGrath 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

binfmt_elf: fix PIE execution with randomization disabled

2011-11-02T23:06:58+00:00

The case of address space randomization being disabled in runtime through
randomize_va_space sysctl is not treated properly in load_elf_binary(),
resulting in SIGKILL coming at exec() time for certain PIE-linked binaries
in case the randomization has been disabled at runtime prior to calling
exec().

Handle the randomize_va_space == 0 case the same way as if we were not
supporting .text randomization at all.

Based on original patch by H.J. Lu and Josh Boyer.

Signed-off-by: Jiri Kosina 
Cc: Ingo Molnar 
Cc: Russell King 
Cc: H.J. Lu 
Cc: 
Tested-by: Josh Boyer 
Acked-by: Nicolas Pitre 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

consolidate BINPRM_FLAGS_ENFORCE_NONDUMP handling

2011-07-20T05:43:10+00:00

new helper: would_dump(bprm, file).  Checks if we are allowed to
read the file and if we are not - sets ENFORCE_NODUMP.  Exported,
used in places that previously open-coded the same logics.

Signed-off-by: Al Viro

brk: COMPAT_BRK: fix detection of randomized brk

2011-04-14T23:06:55+00:00

5520e89 ("brk: fix min_brk lower bound computation for COMPAT_BRK")
tried to get the whole logic of brk randomization for legacy
(libc5-based) applications finally right.

It turns out that the way to detect whether brk has actually been
randomized in the end or not introduced by that patch still doesn't work
for those binaries, as reported by Geert:

: /sbin/init from my old m68k ramdisk exists prematurely.
:
: Before the patch:
:
: | brk(0x80005c8e)                         = 0x80006000
:
: After the patch:
:
: | brk(0x80005c8e)                         = 0x80005c8e
:
: Old libc5 considers brk() to have failed if the return value is not
: identical to the requested value.

I don't like it, but currently see no better option than a bit flag in
task_struct to catch the CONFIG_COMPAT_BRK && randomize_va_space == 2
case.

Signed-off-by: Jiri Kosina 
Tested-by: Geert Uytterhoeven 
Reported-by: Geert Uytterhoeven 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6

2011-03-24T03:51:42+00:00

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
  deal with races in /proc/*/{syscall,stack,personality}
  proc: enable writing to /proc/pid/mem
  proc: make check_mem_permission() return an mm_struct on success
  proc: hold cred_guard_mutex in check_mem_permission()
  proc: disable mem_write after exec
  mm: implement access_remote_vm
  mm: factor out main logic of access_process_vm
  mm: use mm_struct to resolve gate vma's in __get_user_pages
  mm: arch: rename in_gate_area_no_task to in_gate_area_no_mm
  mm: arch: make in_gate_area take an mm_struct instead of a task_struct
  mm: arch: make get_gate_vma take an mm_struct instead of a task_struct
  x86: mark associated mm when running a task in 32 bit compatibility mode
  x86: add context tag to mark mm when running a task in 32-bit compatibility mode
  auxv: require the target to be tracable (or yourself)
  close race in /proc/*/environ
  report errors in /proc/*/*map* sanely
  pagemap: close races with suid execve
  make sessionid permissions in /proc/*/task/* match those in /proc/*
  fix leaks in path_lookupat()

Fix up trivial conflicts in fs/proc/base.c