• Andrey Ryabinin's avatar
    kasan: fix kmemleak false-positive in kasan_module_alloc() · 45937254
    Andrey Ryabinin authored
    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: default avatarAndrey Ryabinin <aryabinin@virtuozzo.com>
    Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    45937254
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