From: Andrey Ryabinin aryabinin@virtuozzo.com
Kmemleak reports the following leak:
unreferenced object 0xfffffbfff41ea000 (size 20480): comm "modprobe", pid 65199, jiffies 4298875551 (age 542.568s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<ffffffff82354f5e>] kmemleak_alloc+0x4e/0xc0 [<ffffffff8152e718>] __vmalloc_node_range+0x4b8/0x740 [<ffffffff81574072>] kasan_module_alloc+0x72/0xc0 [<ffffffff810efe68>] module_alloc+0x78/0xb0 [<ffffffff812f6a24>] module_alloc_update_bounds+0x14/0x70 [<ffffffff812f8184>] layout_and_allocate+0x16f4/0x3c90 [<ffffffff812faa1f>] load_module+0x2ff/0x6690 [<ffffffff813010b6>] SyS_finit_module+0x136/0x170 [<ffffffff8239bbc9>] system_call_fastpath+0x16/0x1b [<ffffffffffffffff>] 0xffffffffffffffff
kasan_module_alloc() allocates shadow memory for module and frees it on module unloading. It doesn't store the pointer to allocated shadow memory because it could be calculated from the shadowed address, i.e. kasan_mem_to_shadow(addr).
Since kmemleak cannot find pointer to allocated shadow, it thinks that memory leaked.
Use kmemleak_ignore() to tell kmemleak that this is not a leak and shadow memory doesn't contain any pointers.
Signed-off-by: Andrey Ryabinin aryabinin@virtuozzo.com Acked-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org (cherry picked from commit 459372545c9c0d6f491e280dccc8a54a61b60e56) Signed-off-by: Alex Shi alex.shi@linaro.org --- mm/kasan/kasan.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c index 7f97c85..81a2f45 100644 --- a/mm/kasan/kasan.c +++ b/mm/kasan/kasan.c @@ -19,6 +19,7 @@ #include <linux/export.h> #include <linux/init.h> #include <linux/kernel.h> +#include <linux/kmemleak.h> #include <linux/memblock.h> #include <linux/memory.h> #include <linux/mm.h> @@ -444,6 +445,7 @@ int kasan_module_alloc(void *addr, size_t size)
if (ret) { find_vm_area(addr)->flags |= VM_KASAN; + kmemleak_ignore(ret); return 0; }