Subject: Re: [PATCH v4] netdevsim: Zero-initialize memory for new map's value in function nsim_bpf_map_alloc

From: [email-masked]
Date: Thu, 16 Dec 2021 02:50:09 +0000

Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski <[email-masked]>:

On Wed, 15 Dec 2021 19:15:30 +0800 you wrote:
> Zero-initialize memory for new map's value in function nsim_bpf_map_alloc
> since it may cause a potential kernel information leak issue, as follows:
> 1. nsim_bpf_map_alloc calls nsim_map_alloc_elem to allocate elements for
> a new map.
> 2. nsim_map_alloc_elem uses kmalloc to allocate map's value, but doesn't
> zero it.
> 3. A user application can use IOCTL BPF_MAP_LOOKUP_ELEM to get specific
> element's information in the map.
> 4. The kernel function map_lookup_elem will call bpf_map_copy_value to get
> the information allocated at step-2, then use copy_to_user to copy to the
> user buffer.
> This can only leak information for an array map.
> 
> [...]

Here is the summary with links:
  - [v4] netdevsim: Zero-initialize memory for new map's value in function nsim_bpf_map_alloc
    https://git.kernel.org/netdev/net/c/481221775d53

You are awesome, thank you!
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