No description
  • C 98.2%
  • Assembly 1%
  • Makefile 0.3%
  • Shell 0.2%
  • Python 0.1%
Find a file
Repository files (latest commit first)
Filename Latest commit message Latest commit date
Joel Fernandes (Google) 056b89e7e6 module: Make srcu_struct ptr array as read-only
Since commit title ("srcu: Allocate per-CPU data for DEFINE_SRCU() in
modules"), modules that call DEFINE_{STATIC,}SRCU will have a new array
of srcu_struct pointers, which is used by srcu code to initialize and
clean up these structures and save valuable per-cpu reserved space.

There is no reason for this array of pointers to be writable, and can
cause security or other hidden bugs. Mark these are read-only after the
module init has completed.

Tested with the following diff to ensure array not writable:

(diff is a bit reduced to avoid patch command getting confused)
 a/kernel/module.c
 b/kernel/module.c
  -3506,6 +3506,14  static noinline int do_init_module [snip]
 	rcu_assign_pointer(mod->kallsyms, &mod->core_kallsyms);
 #endif
 	module_enable_ro(mod, true);
+
+	if (mod->srcu_struct_ptrs) {
+		// Check if srcu_struct_ptrs access is possible
+		char x = *(char *)mod->srcu_struct_ptrs;
+		*(char *)mod->srcu_struct_ptrs = 0;
+		*(char *)mod->srcu_struct_ptrs = x;
+	}
+
 	mod_tree_remove_init(mod);
 	disable_ro_nx(&mod->init_layout);
 	module_arch_freeing_init(mod);

Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: paulmck@linux.vnet.ibm.com
Cc: rostedt@goodmis.org
Cc: mathieu.desnoyers@efficios.com
Cc: rcu@vger.kernel.org
Cc: kernel-hardening@lists.openwall.com
Cc: kernel-team@android.com
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-05-28 09:03:35 -07:00
arch Merge branch 'akpm' (patches from Andrew) 2019-05-19 12:15:32 -07:00
block for-5.2/block-post-20190516 2019-05-16 19:08:15 -07:00
certs
crypto Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2019-05-07 22:03:58 -07:00
Documentation Merge branch 'akpm' (patches from Andrew) 2019-05-19 12:15:32 -07:00
drivers Kbuild updates for v5.2 (2nd) 2019-05-19 11:53:58 -07:00
fs This pull request contains the following fixes for UBIFS: 2019-05-19 15:22:03 -07:00
include module: Make srcu_struct ptr array as read-only 2019-05-28 09:03:35 -07:00
init initramfs: don't free a non-existent initrd 2019-05-18 15:52:26 -07:00
ipc ipc: do cyclic id allocation for the ipc object. 2019-05-14 19:52:52 -07:00
kernel srcu: Allocate per-CPU data for DEFINE_SRCU() in modules 2019-05-28 09:03:35 -07:00
lib slab: remove /proc/slab_allocators 2019-05-16 15:51:55 -07:00
LICENSES
mm Merge branch 'akpm' (patches from Andrew) 2019-05-19 12:15:32 -07:00
net treewide: prefix header search paths with $(srctree)/ 2019-05-18 11:49:57 +09:00
samples samples: guard sub-directories with CONFIG options 2019-05-18 11:29:01 +09:00
scripts kconfig: use 'else ifneq' for Makefile to improve readability 2019-05-19 09:34:35 +09:00
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-05-13 15:15:00 -07:00
sound sound fixes for 5.2-rc1 2019-05-17 13:57:54 -07:00
tools Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-19 11:20:22 -07:00
usr
virt * ARM: support for SVE and Pointer Authentication in guests, PMU improvements 2019-05-17 10:33:30 -07:00
.clang-format
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes
.gitignore .gitignore: exclude .get_maintainer.ignore and .gitattributes 2019-05-18 11:49:54 +09:00
.mailmap A reasonably busy cycle for docs, including: 2019-05-08 12:42:50 -07:00
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Kbuild updates for v5.2 (2nd) 2019-05-19 11:53:58 -07:00
Makefile Linux 5.2-rc1 2019-05-19 15:47:09 -07:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.