linux-kernel - Re: [PATCH -next] acpi/hmat: fix memory leaks in hmat

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Date:   Tue, 9 Apr 2019 10:25:11 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Qian Cai <cai@....pw>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Keith Busch <keith.busch@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -next] acpi/hmat: fix memory leaks in hmat_init()

On Sat, Apr 6, 2019 at 8:18 PM Qian Cai <cai@....pw> wrote:
>
> The commit 665ac7e92757 ("acpi/hmat: Register processor domain to its
> memory") introduced some memory leaks below due to it fails to release
> the heap memory in an error path, and then the stack __initdata memory
> which reference them get freed during boot renders those heap memory as
> leaks.
>
> unreferenced object 0xc8ff8008349e9400 (size 128):
>   comm "swapper/0", pid 1, jiffies 4294709236 (age 48121.476s)
>   hex dump (first 32 bytes):
>     00 d0 9e 34 08 80 ff 84 d8 00 43 11 00 10 ff ff  ...4......C.....
>     00 00 00 00 ff ff ff ff 00 00 00 00 00 00 00 00  ................
>   backtrace:
>     [<00000000869d4503>] __kmalloc+0x568/0x600
>     [<0000000070fd6afb>] alloc_memory_target+0x50/0xd8
>     [<00000000efa2081e>] srat_parse_mem_affinity+0x58/0x5c
>     [<000000008bfaef74>] acpi_parse_entries_array+0x1c8/0x2c0
>     [<0000000022804877>] acpi_table_parse_entries_array+0x11c/0x138
>     [<00000000ffe9cd34>] acpi_table_parse_entries+0x7c/0xac
>     [<00000000a7023afd>] hmat_init+0x90/0x174
>     [<00000000694a86c1>] do_one_initcall+0x2d8/0x5f8
>     [<0000000024889da9>] do_initcall_level+0x37c/0x3fc
>     [<000000009be02908>] do_basic_setup+0x38/0x50
>     [<0000000037b3ac0a>] kernel_init_freeable+0x194/0x258
>     [<00000000f5741184>] kernel_init+0x18/0x334
>     [<000000007b30f423>] ret_from_fork+0x10/0x18
>     [<000000006c7147a8>] 0xffffffffffffffff
>
> Signed-off-by: Qian Cai <cai@....pw>

Well, the catch is good, but the additional label is sort of excessive IMO.

> ---
>  drivers/acpi/hmat/hmat.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/hmat/hmat.c b/drivers/acpi/hmat/hmat.c
> index b7824a0309f7..c9b8abcf012c 100644
> --- a/drivers/acpi/hmat/hmat.c
> +++ b/drivers/acpi/hmat/hmat.c
> @@ -637,7 +637,7 @@ static __init int hmat_init(void)
>
>         status = acpi_get_table(ACPI_SIG_HMAT, 0, &tbl);
>         if (ACPI_FAILURE(status))

I would just add a hmat_free_structures() call here or rework the
_put_table() logic which is not really straightforward.

> -               return 0;
> +               goto out_free;
>
>         hmat_revision = tbl->revision;
>         switch (hmat_revision) {
> @@ -659,8 +659,9 @@ static __init int hmat_init(void)
>         }
>         hmat_register_targets();
>  out_put:
> -       hmat_free_structures();
>         acpi_put_table(tbl);
> +out_free:
> +       hmat_free_structures();
>         return 0;
>  }
>  subsys_initcall(hmat_init);
> --