linux-toradex.git/kernel/module.c, branch v4.4.106

module: Invalidate signatures on force-loaded modules

2016-08-20T16:09:27+00:00

commit bca014caaa6130e57f69b5bf527967aa8ee70fdd upstream.

Signing a module should only make it trusted by the specific kernel it
was built for, not anything else.  Loading a signed module meant for a
kernel with a different ABI could have interesting effects.
Therefore, treat all signatures as invalid when a module is
force-loaded.

Signed-off-by: Ben Hutchings 
Signed-off-by: Rusty Russell 
Signed-off-by: Greg Kroah-Hartman

modules: fix longstanding /proc/kallsyms vs module insertion race.

2016-03-09T23:34:56+00:00

commit 8244062ef1e54502ef55f54cced659913f244c3e upstream.

For CONFIG_KALLSYMS, we keep two symbol tables and two string tables.
There's one full copy, marked SHF_ALLOC and laid out at the end of the
module's init section.  There's also a cut-down version that only
contains core symbols and strings, and lives in the module's core
section.

After module init (and before we free the module memory), we switch
the mod->symtab, mod->num_symtab and mod->strtab to point to the core
versions.  We do this under the module_mutex.

However, kallsyms doesn't take the module_mutex: it uses
preempt_disable() and rcu tricks to walk through the modules, because
it's used in the oops path.  It's also used in /proc/kallsyms.
There's nothing atomic about the change of these variables, so we can
get the old (larger!) num_symtab and the new symtab pointer; in fact
this is what I saw when trying to reproduce.

By grouping these variables together, we can use a
carefully-dereferenced pointer to ensure we always get one or the
other (the free of the module init section is already done in an RCU
callback, so that's safe).  We allocate the init one at the end of the
module init section, and keep the core one inside the struct module
itself (it could also have been allocated at the end of the module
core, but that's probably overkill).

[ Rebased for 4.4-stable and older, because the following changes aren't
  in the older trees:
  - e0224418516b4d8a6c2160574bac18447c354ef0: adds arg to is_core_symbol
  - 7523e4dc5057e157212b4741abd6256e03404cf1: module_init/module_core/init_size/core_size
    become init_layout.base/core_layout.base/init_layout.size/core_layout.size.
]

Reported-by: Weilong Chen 
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=111541
Cc: stable@kernel.org
Signed-off-by: Rusty Russell 
Signed-off-by: Greg Kroah-Hartman

modules: fix modparam async_probe request

2016-02-25T20:01:25+00:00

commit 4355efbd80482a961cae849281a8ef866e53d55c upstream.

Commit f2411da746985 ("driver-core: add driver module
asynchronous probe support") added async probe support,
in two forms:

  * in-kernel driver specification annotation
  * generic async_probe module parameter (modprobe foo async_probe)

To support the generic kernel parameter parse_args() was
extended via commit ecc8617053e0 ("module: add extra
argument for parse_params() callback") however commit
failed to f2411da746985 failed to add the required argument.

This causes a crash then whenever async_probe generic
module parameter is used. This was overlooked when the
form in which in-kernel async probe support was reworked
a bit... Fix this as originally intended.

Cc: Hannes Reinecke 
Cc: Dmitry Torokhov 
Signed-off-by: Luis R. Rodriguez 
Signed-off-by: Rusty Russell  [minimized]
Signed-off-by: Greg Kroah-Hartman

module: wrapper for symbol name.

2016-02-25T20:01:25+00:00

commit 2e7bac536106236104e9e339531ff0fcdb7b8147 upstream.

This trivial wrapper adds clarity and makes the following patch
smaller.

Signed-off-by: Rusty Russell 
Signed-off-by: Greg Kroah-Hartman

ftrace/module: Call clean up function when module init fails early

2016-01-07T17:17:39+00:00

If the module init code fails after calling ftrace_module_init() and before
calling do_init_module(), we can suffer from a memory leak. This is because
ftrace_module_init() allocates pages to store the locations that ftrace
hooks are placed in the module text. If do_init_module() fails, it still
calls the MODULE_GOING notifiers which will tell ftrace to do a clean up of
the pages it allocated for the module. But if load_module() fails before
then, the pages allocated by ftrace_module_init() will never be freed.

Call ftrace_release_mod() on the module if load_module() fails before
getting to do_init_module().

Link: http://lkml.kernel.org/r/567CEA31.1070507@intel.com

Reported-by: "Qiu, PeiyangX" 
Fixes: a949ae560a511 "ftrace/module: Hardcode ftrace_module_init() call into load_module()"
Cc: stable@vger.kernel.org # v2.6.38+
Acked-by: Rusty Russell 
Signed-off-by: Steven Rostedt

module: Fix locking in symbol_put_addr()

2015-08-24T01:07:01+00:00

Poma (on the way to another bug) reported an assertion triggering:

  [] module_assert_mutex_or_preempt+0x49/0x90
  [] __module_address+0x32/0x150
  [] __module_text_address+0x16/0x70
  [] symbol_put_addr+0x29/0x40
  [] dvb_frontend_detach+0x7d/0x90 [dvb_core]

Laura Abbott  produced a patch which lead us to
inspect symbol_put_addr(). This function has a comment claiming it
doesn't need to disable preemption around the module lookup
because it holds a reference to the module it wants to find, which
therefore cannot go away.

This is wrong (and a false optimization too, preempt_disable() is really
rather cheap, and I doubt any of this is on uber critical paths,
otherwise it would've retained a pointer to the actual module anyway and
avoided the second lookup).

While its true that the module cannot go away while we hold a reference
on it, the data structure we do the lookup in very much _CAN_ change
while we do the lookup. Therefore fix the comment and add the
required preempt_disable().

Reported-by: poma 
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Rusty Russell 
Fixes: a6e6abd575fc ("module: remove module_text_address()")
Cc: stable@kernel.org

module: weaken locking assertion for oops path.

2015-07-28T20:43:22+00:00

We don't actually hold the module_mutex when calling find_module_all
from module_kallsyms_lookup_name: that's because it's used by the oops
code and we don't want to deadlock.

However, access to the list read-only is safe if preempt is disabled,
so we can weaken the assertion.  Keep a strong version for external
callers though.

Fixes: 0be964be0d45 ("module: Sanitize RCU usage and locking")
Reported-by: He Kuang 
Cc: stable@kernel.org
Acked-by: Peter Zijlstra (Intel) 
Signed-off-by: Rusty Russell

module: Fix load_module() error path

2015-07-08T21:27:12+00:00

The load_module() error path frees a module but forgot to take it out
of the mod_tree, leaving a dangling entry in the tree, causing havoc.

Cc: Mathieu Desnoyers 
Reported-by: Arthur Marsh 
Tested-by: Arthur Marsh 
Fixes: 93c2e105f6bc ("module: Optimize __module_address() using a latched RB-tree")
Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Rusty Russell

Merge tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

2015-07-01T17:49:25+00:00

Pull module updates from Rusty Russell:
 "Main excitement here is Peter Zijlstra's lockless rbtree optimization
  to speed module address lookup.  He found some abusers of the module
  lock doing that too.

  A little bit of parameter work here too; including Dan Streetman's
  breaking up the big param mutex so writing a parameter can load
  another module (yeah, really).  Unfortunately that broke the usual
  suspects, !CONFIG_MODULES and !CONFIG_SYSFS, so those fixes were
  appended too"

* tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (26 commits)
  modules: only use mod->param_lock if CONFIG_MODULES
  param: fix module param locks when !CONFIG_SYSFS.
  rcu: merge fix for Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE()
  module: add per-module param_lock
  module: make perm const
  params: suppress unused variable error, warn once just in case code changes.
  modules: clarify CONFIG_MODULE_COMPRESS help, suggest 'N'.
  kernel/module.c: avoid ifdefs for sig_enforce declaration
  kernel/workqueue.c: remove ifdefs over wq_power_efficient
  kernel/params.c: export param_ops_bool_enable_only
  kernel/params.c: generalize bool_enable_only
  kernel/module.c: use generic module param operaters for sig_enforce
  kernel/params: constify struct kernel_param_ops uses
  sysfs: tightened sysfs permission checks
  module: Rework module_addr_{min,max}
  module: Use __module_address() for module_address_lookup()
  module: Make the mod_tree stuff conditional on PERF_EVENTS || TRACING
  module: Optimize __module_address() using a latched RB-tree
  rbtree: Implement generic latch_tree
  seqlock: Introduce raw_read_seqcount_latch()
  ...

param: fix module param locks when !CONFIG_SYSFS.

2015-06-28T05:16:14+00:00

As Dan Streetman points out, the entire point of locking for is to
stop sysfs accesses, so they're elided entirely in the !SYSFS case.

Reported-by: Stephen Rothwell 
Signed-off-by: Rusty Russell