[PATCH] mm: Delay kmemleak object creation of module_alloc()

[Kefeng Wang <wangkefeng.wang@huawei.com>]

Yongqiang reports a kmemleak panic when module ismod/rmmod with KASAN
enabled[1] on x86.

The module allocate memory, and it's kmemleak_object is created successfully,
but the KASAN shadow memory of module allocation is not ready, when kmemleak
scan the module's pointer, it will panic due to no shadow memory.

module_alloc
  __vmalloc_node_range
    kmemleak_vmalloc
				kmemleak_scan
				  update_checksum
  kasan_module_alloc
    kmemleak_ignore

The bug should exist on ARM64/S390 too, add a VM_DELAY_KMEMLEAK flags, delay
vmalloc'ed object register of kmemleak in module_alloc().

[1] https://lore.kernel.org/all/6d41e2b9-4692-5ec4-b1cd-cbe29ae89739@huawei.com/
Reported-by: Yongqiang Liu <liuyongqiang13@huawei.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 arch/arm64/kernel/module.c | 4 ++--
 arch/s390/kernel/module.c  | 5 +++--
 arch/x86/kernel/module.c   | 7 ++++---
 include/linux/kasan.h      | 4 ++--
 include/linux/vmalloc.h    | 7 +++++++
 mm/kasan/shadow.c          | 9 +++++++--
 mm/vmalloc.c               | 3 ++-
 7 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
index b5ec010c481f..e6da010716d0 100644
--- a/arch/arm64/kernel/module.c
+++ b/arch/arm64/kernel/module.c
@@ -36,7 +36,7 @@ void *module_alloc(unsigned long size)
 		module_alloc_end = MODULES_END;
 
 	p = __vmalloc_node_range(size, MODULE_ALIGN, module_alloc_base,
-				module_alloc_end, gfp_mask, PAGE_KERNEL, 0,
+				module_alloc_end, gfp_mask, PAGE_KERNEL, VM_DELAY_KMEMLEAK,
 				NUMA_NO_NODE, __builtin_return_address(0));
 
 	if (!p && IS_ENABLED(CONFIG_ARM64_MODULE_PLTS) &&
@@ -58,7 +58,7 @@ void *module_alloc(unsigned long size)
 				PAGE_KERNEL, 0, NUMA_NO_NODE,
 				__builtin_return_address(0));
 
-	if (p && (kasan_module_alloc(p, size) < 0)) {
+	if (p && (kasan_module_alloc(p, size, gfp_mask) < 0)) {
 		vfree(p);
 		return NULL;
 	}
diff --git a/arch/s390/kernel/module.c b/arch/s390/kernel/module.c
index b01ba460b7ca..8d66a93562ca 100644
--- a/arch/s390/kernel/module.c
+++ b/arch/s390/kernel/module.c
@@ -37,14 +37,15 @@
 
 void *module_alloc(unsigned long size)
 {
+	gfp_t gfp_mask = GFP_KERNEL;
 	void *p;
 
 	if (PAGE_ALIGN(size) > MODULES_LEN)
 		return NULL;
 	p = __vmalloc_node_range(size, MODULE_ALIGN, MODULES_VADDR, MODULES_END,
-				 GFP_KERNEL, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
+				 gfp_mask, PAGE_KERNEL_EXEC, VM_DELAY_KMEMLEAK, NUMA_NO_NODE,
 				 __builtin_return_address(0));
-	if (p && (kasan_module_alloc(p, size) < 0)) {
+	if (p && (kasan_module_alloc(p, size, gfp_mask) < 0)) {
 		vfree(p);
 		return NULL;
 	}
diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index 169fb6f4cd2e..ff134d0f1ca1 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -67,6 +67,7 @@ static unsigned long int get_module_load_offset(void)
 
 void *module_alloc(unsigned long size)
 {
+	gfp_t gfp_mask = GFP_KERNEL;
 	void *p;
 
 	if (PAGE_ALIGN(size) > MODULES_LEN)
@@ -74,10 +75,10 @@ void *module_alloc(unsigned long size)
 
 	p = __vmalloc_node_range(size, MODULE_ALIGN,
 				    MODULES_VADDR + get_module_load_offset(),
-				    MODULES_END, GFP_KERNEL,
-				    PAGE_KERNEL, 0, NUMA_NO_NODE,
+				    MODULES_END, gfp_mask,
+				    PAGE_KERNEL, VM_DELAY_KMEMLEAK, NUMA_NO_NODE,
 				    __builtin_return_address(0));
-	if (p && (kasan_module_alloc(p, size) < 0)) {
+	if (p && (kasan_module_alloc(p, size, gfp_mask) < 0)) {
 		vfree(p);
 		return NULL;
 	}
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index d8783b682669..89c99e5e67de 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -474,12 +474,12 @@ static inline void kasan_populate_early_vm_area_shadow(void *start,
  * allocations with real shadow memory. With KASAN vmalloc, the special
  * case is unnecessary, as the work is handled in the generic case.
  */
-int kasan_module_alloc(void *addr, size_t size);
+int kasan_module_alloc(void *addr, size_t size, gfp_t gfp_mask);
 void kasan_free_shadow(const struct vm_struct *vm);
 
 #else /* (CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS) && !CONFIG_KASAN_VMALLOC */
 
-static inline int kasan_module_alloc(void *addr, size_t size) { return 0; }
+static inline int kasan_module_alloc(void *addr, size_t size, gfp_t gfp_mask) { return 0; }
 static inline void kasan_free_shadow(const struct vm_struct *vm) {}
 
 #endif /* (CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS) && !CONFIG_KASAN_VMALLOC */
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 6e022cc712e6..56d2b7828b31 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -28,6 +28,13 @@ struct notifier_block;		/* in notifier.h */
 #define VM_MAP_PUT_PAGES	0x00000200	/* put pages and free array in vfree */
 #define VM_NO_HUGE_VMAP		0x00000400	/* force PAGE_SIZE pte mapping */
 
+#if defined(CONFIG_KASAN) && (defined(CONFIG_KASAN_GENERIC) || \
+	defined(CONFIG_KASAN_SW_TAGS)) && !defined(CONFIG_KASAN_VMALLOC)
+#define VM_DELAY_KMEMLEAK	0x00000800	/* delay kmemleak object create */
+#else
+#define VM_DELAY_KMEMLEAK	0
+#endif
+
 /*
  * VM_KASAN is used slightly differently depending on CONFIG_KASAN_VMALLOC.
  *
diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
index 4a4929b29a23..6ca43b43419b 100644
--- a/mm/kasan/shadow.c
+++ b/mm/kasan/shadow.c
@@ -498,7 +498,7 @@ void kasan_release_vmalloc(unsigned long start, unsigned long end,
 
 #else /* CONFIG_KASAN_VMALLOC */
 
-int kasan_module_alloc(void *addr, size_t size)
+int kasan_module_alloc(void *addr, size_t size, gfp_mask)
 {
 	void *ret;
 	size_t scaled_size;
@@ -520,9 +520,14 @@ int kasan_module_alloc(void *addr, size_t size)
 			__builtin_return_address(0));
 
 	if (ret) {
+		struct vm_struct *vm = find_vm_area(addr);
 		__memset(ret, KASAN_SHADOW_INIT, shadow_size);
-		find_vm_area(addr)->flags |= VM_KASAN;
+		vm->flags |= VM_KASAN;
 		kmemleak_ignore(ret);
+
+		if (vm->flags | VM_DELAY_KMEMLEAK)
+			kmemleak_vmalloc(vm, size, gfp_mask);
+
 		return 0;
 	}
 
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index d2a00ad4e1dd..23c595b15839 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3074,7 +3074,8 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
 	clear_vm_uninitialized_flag(area);
 
 	size = PAGE_ALIGN(size);
-	kmemleak_vmalloc(area, size, gfp_mask);
+	if (!(vm_flags & VM_DELAY_KMEMLEAK))
+		kmemleak_vmalloc(area, size, gfp_mask);
 
 	return addr;
 
-- 
2.26.2