[PATCH v2] mm: Delay kmemleak object creation of module_alloc()
Kefeng Wang
wangkefeng.wang at huawei.com
Tue Nov 23 06:32:20 PST 2021
Yongqiang reports a kmemleak panic when module insmod/rmmod with KASAN
enabled on x86[1].
When the module allocates memory, it's kmemleak_object is created successfully,
but the KASAN shadow memory of module allocation is not ready, so when kmemleak
scan the module's pointer, it will panic due to no shadow memory with KASAN.
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 at huawei.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang at huawei.com>
---
v2:
- fix type error on changelog and kasan_module_alloc()
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..2ade2f484562 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_t 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;
--
2.27.0
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