Re: [PATCH RFC v1 19/26] kmsan: call KMSAN hooks where needed

[Qian Cai <cai@lca.pw>]

On Fri, 2019-10-18 at 11:42 +0200, glider@google.com wrote:
> Insert KMSAN hooks that check for potential memory errors and/or make
> necessary bookkeeping changes:
>  - allocate/split/deallocate metadata pages in
>    alloc_pages()/split_page()/free_page();

This also seems unnecessary where there are options like page_poison and
debug_pagealloc should be able detect uninitialized memory access in the page
allocator as well. Even KASAN has some of the functionality.

>  - clear page shadow and origins in clear_page(), copy_user_highpage();
>  - copy page metadata in copy_highpage(), wp_page_copy();
>  - handle vmap()/vunmap()/iounmap();
>  - handle task creation and deletion;
>  - handle vprintk();
>  - call softirq entry/exit hooks in kernel/softirq.c;
>  - check/initialize memory sent to/read from USB, I2C, and network
> 
> Signed-off-by: Alexander Potapenko <glider@google.com>
> To: Alexander Potapenko <glider@google.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Wolfram Sang <wsa@the-dreams.de>
> Cc: Petr Mladek <pmladek@suse.com>
> Cc: Vegard Nossum <vegard.nossum@oracle.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: linux-mm@kvack.org
> ---
> 
> Change-Id: I1250a928d9263bf71fdaa067a070bdee686ef47b
> ---
>  arch/x86/include/asm/page_64.h | 13 +++++++++++++
>  arch/x86/mm/ioremap.c          |  3 +++
>  drivers/i2c/i2c-core-base.c    |  2 ++
>  drivers/usb/core/urb.c         |  2 ++
>  include/linux/highmem.h        |  4 ++++
>  kernel/exit.c                  |  2 ++
>  kernel/fork.c                  |  2 ++
>  kernel/kthread.c               |  2 ++
>  kernel/printk/printk.c         |  8 +++++++-
>  kernel/softirq.c               |  5 +++++
>  lib/ioremap.c                  |  5 +++++
>  mm/compaction.c                |  9 +++++++++
>  mm/gup.c                       |  3 +++
>  mm/memory.c                    |  2 ++
>  mm/page_alloc.c                | 16 ++++++++++++++++
>  mm/vmalloc.c                   | 23 +++++++++++++++++++++--
>  net/sched/sch_generic.c        |  2 ++
>  17 files changed, 100 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/include/asm/page_64.h b/arch/x86/include/asm/page_64.h
> index 939b1cff4a7b..0ba43d93414f 100644
> --- a/arch/x86/include/asm/page_64.h
> +++ b/arch/x86/include/asm/page_64.h
> @@ -44,14 +44,27 @@ void clear_page_orig(void *page);
>  void clear_page_rep(void *page);
>  void clear_page_erms(void *page);
>  
> +/* This is an assembly header, avoid including too much of kmsan.h */
> +#ifdef CONFIG_KMSAN
> +void kmsan_clear_page(void *page_addr);
> +#endif
> +__no_sanitize_memory
>  static inline void clear_page(void *page)
>  {
> +#ifdef CONFIG_KMSAN
> +	/* alternative_call_2() changes |page|. */
> +	void *page_copy = page;
> +#endif
>  	alternative_call_2(clear_page_orig,
>  			   clear_page_rep, X86_FEATURE_REP_GOOD,
>  			   clear_page_erms, X86_FEATURE_ERMS,
>  			   "=D" (page),
>  			   "0" (page)
>  			   : "cc", "memory", "rax", "rcx");
> +#ifdef CONFIG_KMSAN
> +	/* Clear KMSAN shadow for the pages that have it. */
> +	kmsan_clear_page(page_copy);
> +#endif
>  }
>  
>  void copy_page(void *to, void *from);
> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
> index a39dcdb5ae34..fdb2abc11a82 100644
> --- a/arch/x86/mm/ioremap.c
> +++ b/arch/x86/mm/ioremap.c
> @@ -7,6 +7,7 @@
>   * (C) Copyright 1995 1996 Linus Torvalds
>   */
>  
> +#include <linux/kmsan.h>
>  #include <linux/memblock.h>
>  #include <linux/init.h>
>  #include <linux/io.h>
> @@ -451,6 +452,8 @@ void iounmap(volatile void __iomem *addr)
>  		return;
>  	}
>  
> +	kmsan_iounmap_page_range((unsigned long)addr,
> +		(unsigned long)addr + get_vm_area_size(p));
>  	free_memtype(p->phys_addr, p->phys_addr + get_vm_area_size(p));
>  
>  	/* Finally remove it */
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index 5f6a4985f2bc..9685d3399c79 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -27,6 +27,7 @@
>  #include <linux/irqflags.h>
>  #include <linux/jump_label.h>
>  #include <linux/kernel.h>
> +#include <linux/kmsan.h>
>  #include <linux/module.h>
>  #include <linux/mutex.h>
>  #include <linux/of_device.h>
> @@ -1975,6 +1976,7 @@ int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
>  				trace_i2c_write(adap, &msgs[i], i);
>  	}
>  
> +	kmsan_handle_i2c_transfer(msgs, num);
>  	/* Retry automatically on arbitration loss */
>  	orig_jiffies = jiffies;
>  	for (ret = 0, try = 0; try <= adap->retries; try++) {
> diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
> index 0eab79f82ce4..5bdb54d71c2e 100644
> --- a/drivers/usb/core/urb.c
> +++ b/drivers/usb/core/urb.c
> @@ -8,6 +8,7 @@
>  #include <linux/bitops.h>
>  #include <linux/slab.h>
>  #include <linux/log2.h>
> +#include <linux/kmsan-checks.h>
>  #include <linux/usb.h>
>  #include <linux/wait.h>
>  #include <linux/usb/hcd.h>
> @@ -401,6 +402,7 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
>  			URB_SETUP_MAP_SINGLE | URB_SETUP_MAP_LOCAL |
>  			URB_DMA_SG_COMBINED);
>  	urb->transfer_flags |= (is_out ? URB_DIR_OUT : URB_DIR_IN);
> +	kmsan_handle_urb(urb, is_out);
>  
>  	if (xfertype != USB_ENDPOINT_XFER_CONTROL &&
>  			dev->state < USB_STATE_CONFIGURED)
> diff --git a/include/linux/highmem.h b/include/linux/highmem.h
> index ea5cdbd8c2c3..623b56f48685 100644
> --- a/include/linux/highmem.h
> +++ b/include/linux/highmem.h
> @@ -5,6 +5,7 @@
>  #include <linux/fs.h>
>  #include <linux/kernel.h>
>  #include <linux/bug.h>
> +#include <linux/kmsan.h>
>  #include <linux/mm.h>
>  #include <linux/uaccess.h>
>  #include <linux/hardirq.h>
> @@ -255,6 +256,8 @@ static inline void copy_user_highpage(struct page *to, struct page *from,
>  	vfrom = kmap_atomic(from);
>  	vto = kmap_atomic(to);
>  	copy_user_page(vto, vfrom, vaddr, to);
> +	/* User pages don't have shadow, just clear the destination. */
> +	kmsan_clear_page(page_address(to));
>  	kunmap_atomic(vto);
>  	kunmap_atomic(vfrom);
>  }
> @@ -270,6 +273,7 @@ static inline void copy_highpage(struct page *to, struct page *from)
>  	vfrom = kmap_atomic(from);
>  	vto = kmap_atomic(to);
>  	copy_page(vto, vfrom);
> +	kmsan_copy_page_meta(to, from);
>  	kunmap_atomic(vto);
>  	kunmap_atomic(vfrom);
>  }
> diff --git a/kernel/exit.c b/kernel/exit.c
> index a46a50d67002..9e3ce929110b 100644
> --- a/kernel/exit.c
> +++ b/kernel/exit.c
> @@ -60,6 +60,7 @@
>  #include <linux/writeback.h>
>  #include <linux/shm.h>
>  #include <linux/kcov.h>
> +#include <linux/kmsan.h>
>  #include <linux/random.h>
>  #include <linux/rcuwait.h>
>  #include <linux/compat.h>
> @@ -719,6 +720,7 @@ void __noreturn do_exit(long code)
>  
>  	profile_task_exit(tsk);
>  	kcov_task_exit(tsk);
> +	kmsan_task_exit(tsk);
>  
>  	WARN_ON(blk_needs_flush_plug(tsk));
>  
> diff --git a/kernel/fork.c b/kernel/fork.c
> index bcdf53125210..0f08952a42dc 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -37,6 +37,7 @@
>  #include <linux/fdtable.h>
>  #include <linux/iocontext.h>
>  #include <linux/key.h>
> +#include <linux/kmsan.h>
>  #include <linux/binfmts.h>
>  #include <linux/mman.h>
>  #include <linux/mmu_notifier.h>
> @@ -931,6 +932,7 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
>  	account_kernel_stack(tsk, 1);
>  
>  	kcov_task_init(tsk);
> +	kmsan_task_create(tsk);
>  
>  #ifdef CONFIG_FAULT_INJECTION
>  	tsk->fail_nth = 0;
> diff --git a/kernel/kthread.c b/kernel/kthread.c
> index 621467c33fef..9b948559a34a 100644
> --- a/kernel/kthread.c
> +++ b/kernel/kthread.c
> @@ -17,6 +17,7 @@
>  #include <linux/unistd.h>
>  #include <linux/file.h>
>  #include <linux/export.h>
> +#include <linux/kmsan.h>
>  #include <linux/mutex.h>
>  #include <linux/slab.h>
>  #include <linux/freezer.h>
> @@ -350,6 +351,7 @@ struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data),
>  		set_cpus_allowed_ptr(task, cpu_all_mask);
>  	}
>  	kfree(create);
> +	kmsan_task_create(task);
>  	return task;
>  }
>  
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index ca65327a6de8..f77fdcb5f861 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -1914,7 +1914,12 @@ int vprintk_store(int facility, int level,
>  	 * The printf needs to come first; we need the syslog
>  	 * prefix which might be passed-in as a parameter.
>  	 */
> -	text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
> +	/*
> +	 * We've checked the printk arguments in vprintk_emit() already.
> +	 * Initialize |text_len| to prevent the errors from spreading.
> +	 */
> +	text_len = KMSAN_INIT_VALUE(vscnprintf(text, sizeof(textbuf), fmt,
> +					       args));
>  
>  	/* mark and strip a trailing newline */
>  	if (text_len && text[text_len-1] == '\n') {
> @@ -1972,6 +1977,7 @@ asmlinkage int vprintk_emit(int facility, int level,
>  	boot_delay_msec(level);
>  	printk_delay();
>  
> +	kmsan_handle_vprintk(&fmt, args);
>  	/* This stops the holder of console_sem just where we want him */
>  	logbuf_lock_irqsave(flags);
>  	curr_log_seq = log_next_seq;
> diff --git a/kernel/softirq.c b/kernel/softirq.c
> index 0427a86743a4..6d566dd68b35 100644
> --- a/kernel/softirq.c
> +++ b/kernel/softirq.c
> @@ -11,6 +11,7 @@
>  
>  #include <linux/export.h>
>  #include <linux/kernel_stat.h>
> +#include <linux/kmsan.h>
>  #include <linux/interrupt.h>
>  #include <linux/init.h>
>  #include <linux/mm.h>
> @@ -370,7 +371,9 @@ static inline void invoke_softirq(void)
>  		 * it is the irq stack, because it should be near empty
>  		 * at this stage.
>  		 */
> +		kmsan_softirq_enter();
>  		__do_softirq();
> +		kmsan_softirq_exit();
>  #else
>  		/*
>  		 * Otherwise, irq_exit() is called on the task stack that can
> @@ -600,7 +603,9 @@ static void run_ksoftirqd(unsigned int cpu)
>  		 * We can safely run softirq on inline stack, as we are not deep
>  		 * in the task stack here.
>  		 */
> +		kmsan_softirq_enter();
>  		__do_softirq();
> +		kmsan_softirq_exit();
>  		local_irq_enable();
>  		cond_resched();
>  		return;
> diff --git a/lib/ioremap.c b/lib/ioremap.c
> index 0a2ffadc6d71..5f830cee5bfc 100644
> --- a/lib/ioremap.c
> +++ b/lib/ioremap.c
> @@ -6,6 +6,7 @@
>   *
>   * (C) Copyright 1995 1996 Linus Torvalds
>   */
> +#include <linux/kmsan.h>
>  #include <linux/vmalloc.h>
>  #include <linux/mm.h>
>  #include <linux/sched.h>
> @@ -214,6 +215,8 @@ int ioremap_page_range(unsigned long addr,
>  	unsigned long start;
>  	unsigned long next;
>  	int err;
> +	unsigned long old_addr = addr;
> +	phys_addr_t old_phys_addr = phys_addr;
>  
>  	might_sleep();
>  	BUG_ON(addr >= end);
> @@ -228,6 +231,8 @@ int ioremap_page_range(unsigned long addr,
>  	} while (pgd++, phys_addr += (next - addr), addr = next, addr != end);
>  
>  	flush_cache_vmap(start, end);
> +	if (!err)
> +		kmsan_ioremap_page_range(old_addr, end, old_phys_addr, prot);
>  
>  	return err;
>  }
> diff --git a/mm/compaction.c b/mm/compaction.c
> index ce08b39d85d4..e9a5898e5fe0 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -84,6 +84,15 @@ static void split_map_pages(struct list_head *list)
>  
>  		for (i = 0; i < nr_pages; i++) {
>  			list_add(&page->lru, &tmp_list);
> +#ifdef CONFIG_KMSAN
> +			/*
> +			 * TODO(glider): we may lose the metadata when copying
> +			 * something to these pages. Need to allocate shadow
> +			 * and origin pages here instead.
> +			 */
> +			page->shadow = NULL;
> +			page->origin = NULL;
> +#endif
>  			page++;
>  		}
>  	}
> diff --git a/mm/gup.c b/mm/gup.c
> index 23a9f9c9d377..c16e4288997d 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -4,6 +4,7 @@
>  #include <linux/err.h>
>  #include <linux/spinlock.h>
>  
> +#include <linux/kmsan.h>
>  #include <linux/mm.h>
>  #include <linux/memremap.h>
>  #include <linux/pagemap.h>
> @@ -2347,6 +2348,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
>  	    gup_fast_permitted(start, end)) {
>  		local_irq_save(flags);
>  		gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr);
> +		kmsan_gup_pgd_range(pages, nr);
>  		local_irq_restore(flags);
>  	}
>  
> @@ -2416,6 +2418,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
>  	    gup_fast_permitted(start, end)) {
>  		local_irq_disable();
>  		gup_pgd_range(addr, end, gup_flags, pages, &nr);
> +		kmsan_gup_pgd_range(pages, nr);
>  		local_irq_enable();
>  		ret = nr;
>  	}
> diff --git a/mm/memory.c b/mm/memory.c
> index b1ca51a079f2..48ceacc06e2d 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -51,6 +51,7 @@
>  #include <linux/highmem.h>
>  #include <linux/pagemap.h>
>  #include <linux/memremap.h>
> +#include <linux/kmsan.h>
>  #include <linux/ksm.h>
>  #include <linux/rmap.h>
>  #include <linux/export.h>
> @@ -2328,6 +2329,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
>  		if (!new_page)
>  			goto oom;
>  		cow_user_page(new_page, old_page, vmf->address, vma);
> +		kmsan_copy_page_meta(new_page, old_page);
>  	}
>  
>  	if (mem_cgroup_try_charge_delay(new_page, mm, GFP_KERNEL, &memcg, false))
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index c0b2e0306720..f52494e0dcd9 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -26,6 +26,8 @@
>  #include <linux/compiler.h>
>  #include <linux/kernel.h>
>  #include <linux/kasan.h>
> +#include <linux/kmsan.h>
> +#include <linux/kmsan-checks.h>
>  #include <linux/module.h>
>  #include <linux/suspend.h>
>  #include <linux/pagevec.h>
> @@ -1133,6 +1135,7 @@ static __always_inline bool free_pages_prepare(struct page *page,
>  	VM_BUG_ON_PAGE(PageTail(page), page);
>  
>  	trace_mm_page_free(page, order);
> +	kmsan_free_page(page, order);
>  
>  	/*
>  	 * Check tail pages before head page information is cleared to
> @@ -3121,6 +3124,7 @@ void split_page(struct page *page, unsigned int order)
>  	VM_BUG_ON_PAGE(PageCompound(page), page);
>  	VM_BUG_ON_PAGE(!page_count(page), page);
>  
> +	kmsan_split_page(page, order);
>  	for (i = 1; i < (1 << order); i++)
>  		set_page_refcounted(page + i);
>  	split_page_owner(page, order);
> @@ -3253,6 +3257,13 @@ static struct page *rmqueue_pcplist(struct zone *preferred_zone,
>  /*
>   * Allocate a page from the given zone. Use pcplists for order-0 allocations.
>   */
> +/*
> + * TODO(glider): rmqueue() may call __msan_poison_alloca() through a call to
> + * set_pfnblock_flags_mask(). If __msan_poison_alloca() attempts to allocate
> + * pages for the stack depot, it may call rmqueue() again, which will result
> + * in a deadlock.
> + */
> +__no_sanitize_memory
>  static inline
>  struct page *rmqueue(struct zone *preferred_zone,
>  			struct zone *zone, unsigned int order,
> @@ -4779,6 +4790,11 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
>  
>  	trace_mm_page_alloc(page, order, alloc_mask, ac.migratetype);
>  
> +	if (page)
> +		if (kmsan_alloc_page(page, order, gfp_mask)) {
> +			__free_pages(page, order);
> +			page = NULL;
> +		}
>  	return page;
>  }
>  EXPORT_SYMBOL(__alloc_pages_nodemask);
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index a3c70e275f4e..bdf66ffcf02c 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -29,6 +29,7 @@
>  #include <linux/rcupdate.h>
>  #include <linux/pfn.h>
>  #include <linux/kmemleak.h>
> +#include <linux/kmsan.h>
>  #include <linux/atomic.h>
>  #include <linux/compiler.h>
>  #include <linux/llist.h>
> @@ -119,7 +120,8 @@ static void vunmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end)
>  	} while (p4d++, addr = next, addr != end);
>  }
>  
> -static void vunmap_page_range(unsigned long addr, unsigned long end)
> +/* Exported for KMSAN, visible in mm/kmsan/kmsan.h only. */
> +void __vunmap_page_range(unsigned long addr, unsigned long end)
>  {
>  	pgd_t *pgd;
>  	unsigned long next;
> @@ -133,6 +135,12 @@ static void vunmap_page_range(unsigned long addr, unsigned long end)
>  		vunmap_p4d_range(pgd, addr, next);
>  	} while (pgd++, addr = next, addr != end);
>  }
> +EXPORT_SYMBOL(__vunmap_page_range);
> +static void vunmap_page_range(unsigned long addr, unsigned long end)
> +{
> +	kmsan_vunmap_page_range(addr, end);
> +	__vunmap_page_range(addr, end);
> +}
>  
>  static int vmap_pte_range(pmd_t *pmd, unsigned long addr,
>  		unsigned long end, pgprot_t prot, struct page **pages, int *nr)
> @@ -216,8 +224,11 @@ static int vmap_p4d_range(pgd_t *pgd, unsigned long addr,
>   * will have pfns corresponding to the "pages" array.
>   *
>   * Ie. pte at addr+N*PAGE_SIZE shall point to pfn corresponding to pages[N]
> + *
> + * This function is exported for use in KMSAN, but is only declared in KMSAN
> + * headers.
>   */
> -static int vmap_page_range_noflush(unsigned long start, unsigned long end,
> +int __vmap_page_range_noflush(unsigned long start, unsigned long end,
>  				   pgprot_t prot, struct page **pages)
>  {
>  	pgd_t *pgd;
> @@ -237,6 +248,14 @@ static int vmap_page_range_noflush(unsigned long start, unsigned long end,
>  
>  	return nr;
>  }
> +EXPORT_SYMBOL(__vmap_page_range_noflush);
> +
> +static int vmap_page_range_noflush(unsigned long start, unsigned long end,
> +				   pgprot_t prot, struct page **pages)
> +{
> +	kmsan_vmap_page_range_noflush(start, end, prot, pages);
> +	return __vmap_page_range_noflush(start, end, prot, pages);
> +}
>  
>  static int vmap_page_range(unsigned long start, unsigned long end,
>  			   pgprot_t prot, struct page **pages)
> diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
> index 17bd8f539bc7..fd22c4a4ba42 100644
> --- a/net/sched/sch_generic.c
> +++ b/net/sched/sch_generic.c
> @@ -11,6 +11,7 @@
>  #include <linux/module.h>
>  #include <linux/types.h>
>  #include <linux/kernel.h>
> +#include <linux/kmsan-checks.h>
>  #include <linux/sched.h>
>  #include <linux/string.h>
>  #include <linux/errno.h>
> @@ -659,6 +660,7 @@ static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
>  	} else {
>  		qdisc->empty = true;
>  	}
> +	kmsan_check_skb(skb);
>  
>  	return skb;
>  }