On Thu, Nov 13, 2014 at 01:20:20PM +0100, Thierry Reding wrote:

> kmemleak started complaining for me recently and the stacktrace (see
> below) points to this function:
> 
>       unreferenced object 0xec0f77c0 (size 192):
>         comm "kworker/u8:0", pid 169, jiffies 4294939367 (age 86.360s)
>         hex dump (first 32 bytes):
>           01 00 00 70 1c ef 01 00 1c ef 01 00 1c ef 01 00  ...p............
>           a0 00 00 00 a0 00 00 00 04 00 00 00 04 00 00 00  ................
>         backtrace:
>           [<c00ec080>] __kmalloc+0x104/0x190
>           [<c01387d4>] load_elf_phdrs+0x60/0x8c
>           [<c0138cb4>] load_elf_binary+0x280/0x12d8
>           [<c00f8ef0>] search_binary_handler+0x80/0x1f0
>           [<c00fa370>] do_execveat_common+0x570/0x658
>           [<c00fa480>] do_execve+0x28/0x30
>           [<c0038eb4>] ____call_usermodehelper+0x144/0x19c
>           [<c000e638>] ret_from_fork+0x14/0x3c
>           [<ffffffff>] 0xffffffff
[...]
> I think what happens is that the interp_elf_phdata memory is freed only
> in the error cleanup path, but not when the function actually succeeds.
> 
> The attached patch plugs the leak for me.
> 
> Thierry

> diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
> index f95da60e440e..8a9be83e88c2 100644
> --- a/fs/binfmt_elf.c
> +++ b/fs/binfmt_elf.c
> @@ -1029,6 +1029,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
>               }
>       }
>  
> +     kfree(interp_elf_phdata);
>       kfree(elf_phdata);
>  
>       set_binfmt(&elf_format);

Folded in and testing now.

  Ralf
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