From: Haimin Zhang tcs.kernel@gmail.com

mainline inclusion from mainline-5.16-rc6 commit 481221775d53d6215a6e5e9ce1cce6d2b4ab9a46 category: bugfix CVE: CVE-2021-4135

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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.

Fixes: 395cacb5f1a0 ("netdevsim: bpf: support fake map offload") Suggested-by: Jakub Kicinski kuba@kernel.org Acked-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Haimin Zhang tcs.kernel@gmail.com Link: https://lore.kernel.org/r/20211215111530.72103-1-tcs.kernel@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Zhengchao Shao shaozhengchao@huawei.com Reviewed-by: Wei Yongjun weiyongjun1@huawei.com Reviewed-by: Yue Haibing yuehaibing@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/net/netdevsim/bpf.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/drivers/net/netdevsim/bpf.c b/drivers/net/netdevsim/bpf.c index 81444208b2162..12f100392ed11 100644 --- a/drivers/net/netdevsim/bpf.c +++ b/drivers/net/netdevsim/bpf.c @@ -493,6 +493,7 @@ nsim_bpf_map_alloc(struct netdevsim *ns, struct bpf_offloaded_map *offmap) goto err_free; key = nmap->entry[i].key; *key = i; + memset(nmap->entry[i].value, 0, offmap->map.value_size); } }