linux/kernel/module.c, branch v4.0

Copy the kernel module data from user space in chunks

2015-04-08T21:35:48Z

Unlike most (all?) other copies from user space, kernel module loading is almost unlimited in size. So we do a potentially huge "copy_from_user()" when we copy the module data from user space to the kernel buffer, which can be a latency concern when preemption is disabled (or voluntary). Also, because 'copy_from_user()' clears the tail of the kernel buffer on failures, even a *failed* copy can end up wasting a lot of time. Normally neither of these are concerns in real life, but they do trigger when doing stress-testing with trinity. Running in a VM seems to add its own overheadm causing trinity module load testing to even trigger the watchdog. The simple fix is to just chunk up the module loading, so that it never tries to copy insanely big areas in one go. That bounds the latency, and also the amount of (unnecessarily, in this case) cleared memory for the failure case. Reported-by: Sasha Levin Signed-off-by: Linus Torvalds

lockdep: Fix the module unload key range freeing logic

2015-03-23T09:49:07Z

Module unload calls lockdep_free_key_range(), which removes entries from the data structures. Most of the lockdep code OTOH assumes the data structures are append only; in specific see the comments in add_lock_to_list() and look_up_lock_class(). Clearly this has only worked by accident; make it work proper. The actual scenario to make it go boom would involve the memory freed by the module unlock being re-allocated and re-used for a lock inside of a rcu-sched grace period. This is a very unlikely scenario, still better plug the hole. Use RCU list iteration in all places and ammend the comments. Change lockdep_free_key_range() to issue a sync_sched() between removal from the lists and returning -- which results in the memory being freed. Further ensure the callers are placed correctly and comment the requirements. Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Andrey Tsyvarev Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Rusty Russell Cc: Thomas Gleixner Signed-off-by: Ingo Molnar

kasan, module, vmalloc: rework shadow allocation for modules

2015-03-13T01:46:08Z

Current approach in handling shadow memory for modules is broken. Shadow memory could be freed only after memory shadow corresponds it is no longer used. vfree() called from interrupt context could use memory its freeing to store 'struct llist_node' in it: void vfree(const void *addr) { ... if (unlikely(in_interrupt())) { struct vfree_deferred *p = this_cpu_ptr(&vfree_deferred); if (llist_add((struct llist_node *)addr, &p->list)) schedule_work(&p->wq); Later this list node used in free_work() which actually frees memory. Currently module_memfree() called in interrupt context will free shadow before freeing module's memory which could provoke kernel crash. So shadow memory should be freed after module's memory. However, such deallocation order could race with kasan_module_alloc() in module_alloc(). Free shadow right before releasing vm area. At this point vfree()'d memory is not used anymore and yet not available for other allocations. New VM_KASAN flag used to indicate that vm area has dynamically allocated shadow memory so kasan frees shadow only if it was previously allocated. Signed-off-by: Andrey Ryabinin Acked-by: Rusty Russell Cc: Dmitry Vyukov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernel/module.c: Update debug alignment after symtable generation

2015-03-06T12:04:22Z

When CONFIG_DEBUG_SET_MODULE_RONX is enabled, the sizes of module sections are aligned up so appropriate permissions can be applied. Adjusting for the symbol table may cause them to become unaligned. Make sure to re-align the sizes afterward. Signed-off-by: Laura Abbott Acked-by: Rusty Russell Signed-off-by: Catalin Marinas

kernel/module.c: do not inline do_init_module()

2015-02-17T22:34:53Z

This provides a reliable breakpoint target, required for automatic symbol loading via the gdb helper command 'lx-symbols'. Signed-off-by: Jan Kiszka Acked-by: Rusty Russell Cc: Thomas Gleixner Cc: Jason Wessel Cc: Andi Kleen Cc: Ben Widawsky Cc: Borislav Petkov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kasan: enable instrumentation of global variables

2015-02-14T05:21:42Z

This feature let us to detect accesses out of bounds of global variables. This will work as for globals in kernel image, so for globals in modules. Currently this won't work for symbols in user-specified sections (e.g. __init, __read_mostly, ...) The idea of this is simple. Compiler increases each global variable by redzone size and add constructors invoking __asan_register_globals() function. Information about global variable (address, size, size with redzone ...) passed to __asan_register_globals() so we could poison variable's redzone. This patch also forces module_alloc() to return 8*PAGE_SIZE aligned address making shadow memory handling ( kasan_module_alloc()/kasan_module_free() ) more simple. Such alignment guarantees that each shadow page backing modules address space correspond to only one module_alloc() allocation. Signed-off-by: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Konstantin Serebryany Cc: Dmitry Chernenkov Signed-off-by: Andrey Konovalov Cc: Yuri Gribov Cc: Konstantin Khlebnikov Cc: Sasha Levin Cc: Christoph Lameter Cc: Joonsoo Kim Cc: Dave Hansen Cc: Andi Kleen Cc: Ingo Molnar Cc: Thomas Gleixner Cc: "H. Peter Anvin" Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

module: Replace over-engineered nested sleep

2015-02-11T04:32:04Z

Since the introduction of the nested sleep warning; we've established that the occasional sleep inside a wait_event() is fine. wait_event() loops are invariant wrt. spurious wakeups, and the occasional sleep has a similar effect on them. As long as its occasional its harmless. Therefore replace the 'correct' but verbose wait_woken() thing with a simple annotation to shut up the warning. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Rusty Russell

module: Annotate nested sleep in resolve_symbol()

2015-02-11T04:32:04Z

Because wait_event() loops are safe vs spurious wakeups we can allow the occasional sleep -- which ends up being very similar. Reported-by: Dave Jones Signed-off-by: Peter Zijlstra (Intel) Tested-by: Dave Jones Signed-off-by: Rusty Russell

module: Remove double spaces in module verification taint message

2015-02-06T05:01:41Z

The warning message when loading modules with a wrong signature has two spaces in it: "module verification failed: signature and/or required key missing" Signed-off-by: Marcel Holtmann Signed-off-by: Rusty Russell

kernel/module.c: Free lock-classes if parse_args failed

2015-02-06T05:01:40Z

parse_args call module parameters' .set handlers, which may use locks defined in the module. So, these classes should be freed in case parse_args returns error(e.g. due to incorrect parameter passed). Signed-off-by: Andrey Tsyvarev Signed-off-by: Rusty Russell