Re: [Qemu-devel] [PATCH] hw/arm/realview.c: Fix memory leak in realview_init()

[Peter Maydell <peter.maydell@linaro.org>]

On 29 October 2014 14:03, Nikita Belov <zodiac@ispras.ru> wrote:
> Variable 'ram_lo' is allocated unconditionally, but used only in some cases.
> When it is unused pointer will be lost at function exit, resulting in a
> memory leak. Free memory in this case.
>
> Valgrind output:
> ==16879== 240 bytes in 1 blocks are definitely lost in loss record 6,033 of 7,018
> ==16879==    at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==16879==    by 0x33D2CE: malloc_and_trace (vl.c:2804)
> ==16879==    by 0x509E610: g_malloc (in /lib/x86_64-linux-gnu/libglib-2.0.so.0.4000.0)
> ==16879==    by 0x288836: realview_init (realview.c:55)
> ==16879==    by 0x28988C: realview_pb_a8_init (realview.c:375)
> ==16879==    by 0x341426: main (vl.c:4413)
>
> Signed-off-by: Nikita Belov <zodiac@ispras.ru>
> ---
>  hw/arm/realview.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/hw/arm/realview.c b/hw/arm/realview.c
> index af65aa4..673a540 100644
> --- a/hw/arm/realview.c
> +++ b/hw/arm/realview.c
> @@ -141,6 +141,8 @@ static void realview_init(MachineState *machine,
>                                 &error_abort);
>          vmstate_register_ram_global(ram_lo);
>          memory_region_add_subregion(sysmem, 0x20000000, ram_lo);
> +    } else {
> +        g_free(ram_lo);
>      }
>
>      memory_region_init_ram(ram_hi, NULL, "realview.highmem", ram_size,

We leak all of the MemoryRegions we allocate here, because we
don't have a persistent state struct to keep them in. This
doesn't really matter much because they're generally needed
for the lifetime of the QEMU process anyway, and we only call
board init functions once. So why worry about ram_lo in
particular (and why this board in particular)?

thanks
-- PMM