Re: [PATCH bpf-next v5] bpf: Fix use-after-free on mm_struct in bpf_find_vma()

Hi Sanghyun,

kernel test robot noticed the following build errors:

[auto build test ERROR on bpf-next/net]
[also build test ERROR on bpf/master linus/master v7.2-rc7]
[cannot apply to bpf-next/master next-20260812]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Sanghyun-Park/bpf-Fix-use-after-free-on-mm_struct-in-bpf_find_vma/20260813-193715
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git net
patch link:    https://lore.kernel.org/r/20260630023443.3026627-2-sanghyun.park.cnu%40gmail.com
patch subject: [PATCH bpf-next v5] bpf: Fix use-after-free on mm_struct in bpf_find_vma()
config: powerpc-allmodconfig (https://download.01.org/0day-ci/archive/20260814/[email protected]/config)
compiler: powerpc64-linux-gcc (GCC) 16.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260814/[email protected]/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All errors (new ones prefixed by >>):

   kernel/bpf/task_iter.c: In function 'bpf_iter_task_vma_destroy':
>> kernel/bpf/task_iter.c:1017:17: error: implicit declaration of function 'bpf_iter_mmput_async' [-Wimplicit-function-declaration]
    1017 |                 bpf_iter_mmput_async(kit->data->mm);
         |                 ^~~~~~~~~~~~~~~~~~~~


vim +/bpf_iter_mmput_async +1017 kernel/bpf/task_iter.c

4ac454682158473 Dave Marchevsky 2023-10-13  1009  
4ac454682158473 Dave Marchevsky 2023-10-13  1010  __bpf_kfunc void bpf_iter_task_vma_destroy(struct bpf_iter_task_vma *it)
4ac454682158473 Dave Marchevsky 2023-10-13  1011  {
4ac454682158473 Dave Marchevsky 2023-10-13  1012  	struct bpf_iter_task_vma_kern *kit = (void *)it;
4ac454682158473 Dave Marchevsky 2023-10-13  1013  
4ac454682158473 Dave Marchevsky 2023-10-13  1014  	if (kit->data) {
4cbee026db54cad Puranjay Mohan  2026-04-08  1015  		bpf_iter_task_vma_snapshot_reset(&kit->data->snapshot);
4ac454682158473 Dave Marchevsky 2023-10-13  1016  		put_task_struct(kit->data->task);
d8e27d2d22b6e2d Puranjay Mohan  2026-04-08 @1017  		bpf_iter_mmput_async(kit->data->mm);
4ac454682158473 Dave Marchevsky 2023-10-13  1018  		bpf_mem_free(&bpf_global_ma, kit->data);
4ac454682158473 Dave Marchevsky 2023-10-13  1019  	}
4ac454682158473 Dave Marchevsky 2023-10-13  1020  }
4ac454682158473 Dave Marchevsky 2023-10-13  1021  

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