From: Andrey Ryabinin Date: Fri, 20 Nov 2015 23:57:18 +0000 (-0800) Subject: kasan: fix kmemleak false-positive in kasan_module_alloc() X-Git-Tag: firefly_0821_release~176^2~647^2~13 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=459372545c9c0d6f491e280dccc8a54a61b60e56;p=firefly-linux-kernel-4.4.55.git kasan: fix kmemleak false-positive in kasan_module_alloc() 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: [] kmemleak_alloc+0x4e/0xc0 [] __vmalloc_node_range+0x4b8/0x740 [] kasan_module_alloc+0x72/0xc0 [] module_alloc+0x78/0xb0 [] module_alloc_update_bounds+0x14/0x70 [] layout_and_allocate+0x16f4/0x3c90 [] load_module+0x2ff/0x6690 [] SyS_finit_module+0x136/0x170 [] system_call_fastpath+0x16/0x1b [] 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 Acked-by: Catalin Marinas Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c index d41b21bce6a0..bc0a8d8b8f42 100644 --- a/mm/kasan/kasan.c +++ b/mm/kasan/kasan.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -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; }