Re: [PATCH v2] bpf: Add length check for SK_DIAG_BPF_STORAGE_REQ_MAP_FD parsing
From: Leon Romanovsky <leon@kernel.org>
Date: 2023-07-25 04:44:30
Also in:
bpf, lkml
On Tue, Jul 25, 2023 at 10:33:30AM +0800, Lin Ma wrote:
quoted hunk ↗ jump to hunk
The nla_for_each_nested parsing in function bpf_sk_storage_diag_alloc does not check the length of the nested attribute. This can lead to an out-of-attribute read and allow a malformed nlattr (e.g., length 0) to be viewed as a 4 byte integer. This patch adds an additional check when the nlattr is getting counted. This makes sure the latter nla_get_u32 can access the attributes with the correct length. Fixes: 1ed4d92458a9 ("bpf: INET_DIAG support in bpf_sk_storage") Suggested-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Lin Ma <redacted> --- V1 -> V2: moves the check to the counting loop as Jakub suggested, alters the commit message accordingly. net/core/bpf_sk_storage.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c index d4172534dfa8..cca7594be92e 100644 --- a/net/core/bpf_sk_storage.c +++ b/net/core/bpf_sk_storage.c@@ -496,8 +496,11 @@ bpf_sk_storage_diag_alloc(const struct nlattr *nla_stgs) return ERR_PTR(-EPERM); nla_for_each_nested(nla, nla_stgs, rem) { - if (nla_type(nla) == SK_DIAG_BPF_STORAGE_REQ_MAP_FD) + if (nla_type(nla) == SK_DIAG_BPF_STORAGE_REQ_MAP_FD) { + if (nla_len(nla) != sizeof(u32))
Jakub, it seems like Lin adds this check to all nla_for_each_nested() loops. IMHO, the better change will be to change nla_for_each_nested() skip empty/not valid NLAs. Thanks
+ return ERR_PTR(-EINVAL); nr_maps++; + } } diag = kzalloc(struct_size(diag, maps, nr_maps), GFP_KERNEL); -- 2.17.1