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SubjectRe: [PATCH v2] kasan: fix kmemleak false-positive in kasan_module_alloc()
On 18 November 2015 at 09:26, Andrey Ryabinin <aryabinin@virtuozzo.com> wrote:
> 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>
> Cc: Catalin Marinas <catalin.marinas@arm.com>

Acked-by: Catalin Marinas <catalin.marinas@arm.com>


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