The memcpy() in ncsi_cmd_handler_oem deserializes nca->data into a
flexible array structure that overlapping with non-flex-array members
(mfr_id) intentionally. Since the mem_to_flex() API is not finished,
temporarily silence this warning, since it is a false positive, using
unsafe_memcpy().
Reported-by: Joel Stanley <[email protected]>
Link: https://lore.kernel.org/netdev/CACPK8Xdfi=OJKP0x0D1w87fQeFZ4A2DP2qzGCRcuVbpU-9=4sQ@mail.gmail.com/
Cc: Samuel Mendoza-Jonas <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
---
net/ncsi/ncsi-cmd.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/ncsi/ncsi-cmd.c b/net/ncsi/ncsi-cmd.c
index dda8b76b7798..fd2236ee9a79 100644
--- a/net/ncsi/ncsi-cmd.c
+++ b/net/ncsi/ncsi-cmd.c
@@ -228,7 +228,8 @@ static int ncsi_cmd_handler_oem(struct sk_buff *skb,
len += max(payload, padding_bytes);
cmd = skb_put_zero(skb, len);
- memcpy(&cmd->mfr_id, nca->data, nca->payload);
+ unsafe_memcpy(&cmd->mfr_id, nca->data, nca->payload,
+ /* skb allocated with enough to load the payload */);
ncsi_cmd_build_header(&cmd->cmd.common, nca);
return 0;
--
2.34.1
Hello,
On Fri, 2022-12-02 at 13:24 -0800, Kees Cook wrote:
> The memcpy() in ncsi_cmd_handler_oem deserializes nca->data into a
> flexible array structure that overlapping with non-flex-array members
> (mfr_id) intentionally. Since the mem_to_flex() API is not finished,
> temporarily silence this warning, since it is a false positive, using
> unsafe_memcpy().
>
> Reported-by: Joel Stanley <[email protected]>
> Link: https://lore.kernel.org/netdev/CACPK8Xdfi=OJKP0x0D1w87fQeFZ4A2DP2qzGCRcuVbpU-9=4sQ@mail.gmail.com/
> Cc: Samuel Mendoza-Jonas <[email protected]>
> Cc: "David S. Miller" <[email protected]>
> Cc: Eric Dumazet <[email protected]>
> Cc: Jakub Kicinski <[email protected]>
> Cc: Paolo Abeni <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>
Is this for the -net or the -net-next tree? It applies to both...
It you are targetting the -net tree, I think it would be nicer adding a
suitable Fixes tag.
Thanks!
Paolo
On Tue, Dec 06, 2022 at 11:36:54AM +0100, Paolo Abeni wrote:
> Hello,
>
> On Fri, 2022-12-02 at 13:24 -0800, Kees Cook wrote:
> > The memcpy() in ncsi_cmd_handler_oem deserializes nca->data into a
> > flexible array structure that overlapping with non-flex-array members
> > (mfr_id) intentionally. Since the mem_to_flex() API is not finished,
> > temporarily silence this warning, since it is a false positive, using
> > unsafe_memcpy().
> >
> > Reported-by: Joel Stanley <[email protected]>
> > Link: https://lore.kernel.org/netdev/CACPK8Xdfi=OJKP0x0D1w87fQeFZ4A2DP2qzGCRcuVbpU-9=4sQ@mail.gmail.com/
> > Cc: Samuel Mendoza-Jonas <[email protected]>
> > Cc: "David S. Miller" <[email protected]>
> > Cc: Eric Dumazet <[email protected]>
> > Cc: Jakub Kicinski <[email protected]>
> > Cc: Paolo Abeni <[email protected]>
> > Cc: [email protected]
> > Signed-off-by: Kees Cook <[email protected]>
>
> Is this for the -net or the -net-next tree? It applies to both...
>
> It you are targetting the -net tree, I think it would be nicer adding a
> suitable Fixes tag.
-net-next (v6.2) is fine -- this is where the warning manifests.
-Kees
--
Kees Cook
Hello:
This patch was applied to netdev/net-next.git (master)
by Jakub Kicinski <[email protected]>:
On Fri, 2 Dec 2022 13:24:22 -0800 you wrote:
> The memcpy() in ncsi_cmd_handler_oem deserializes nca->data into a
> flexible array structure that overlapping with non-flex-array members
> (mfr_id) intentionally. Since the mem_to_flex() API is not finished,
> temporarily silence this warning, since it is a false positive, using
> unsafe_memcpy().
>
> Reported-by: Joel Stanley <[email protected]>
> Link: https://lore.kernel.org/netdev/CACPK8Xdfi=OJKP0x0D1w87fQeFZ4A2DP2qzGCRcuVbpU-9=4sQ@mail.gmail.com/
> Cc: Samuel Mendoza-Jonas <[email protected]>
> Cc: "David S. Miller" <[email protected]>
> Cc: Eric Dumazet <[email protected]>
> Cc: Jakub Kicinski <[email protected]>
> Cc: Paolo Abeni <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>
>
> [...]
Here is the summary with links:
- net/ncsi: Silence runtime memcpy() false positive warning
https://git.kernel.org/netdev/net-next/c/b93884eea26f
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
On Fri, 2 Dec 2022 at 21:24, Kees Cook <[email protected]> wrote:
>
> The memcpy() in ncsi_cmd_handler_oem deserializes nca->data into a
> flexible array structure that overlapping with non-flex-array members
> (mfr_id) intentionally. Since the mem_to_flex() API is not finished,
> temporarily silence this warning, since it is a false positive, using
> unsafe_memcpy().
Thanks for sending the fix Kees. I got a bit busy towards the end of the year.
I spent some time looking at how the netlink api was used, and tried
to convince myself that a user couldn't send an OEM command that
triggered the overflow. It all got a bit tangled up so I didn't come
to a conclusion.
Cheers,
Joel
>
> Reported-by: Joel Stanley <[email protected]>
> Link: https://lore.kernel.org/netdev/CACPK8Xdfi=OJKP0x0D1w87fQeFZ4A2DP2qzGCRcuVbpU-9=4sQ@mail.gmail.com/
> Cc: Samuel Mendoza-Jonas <[email protected]>
> Cc: "David S. Miller" <[email protected]>
> Cc: Eric Dumazet <[email protected]>
> Cc: Jakub Kicinski <[email protected]>
> Cc: Paolo Abeni <[email protected]>
> Cc: [email protected]
> Signed-off-by: Kees Cook <[email protected]>
> ---
> net/ncsi/ncsi-cmd.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/ncsi/ncsi-cmd.c b/net/ncsi/ncsi-cmd.c
> index dda8b76b7798..fd2236ee9a79 100644
> --- a/net/ncsi/ncsi-cmd.c
> +++ b/net/ncsi/ncsi-cmd.c
> @@ -228,7 +228,8 @@ static int ncsi_cmd_handler_oem(struct sk_buff *skb,
> len += max(payload, padding_bytes);
>
> cmd = skb_put_zero(skb, len);
> - memcpy(&cmd->mfr_id, nca->data, nca->payload);
> + unsafe_memcpy(&cmd->mfr_id, nca->data, nca->payload,
> + /* skb allocated with enough to load the payload */);
> ncsi_cmd_build_header(&cmd->cmd.common, nca);
>
> return 0;
> --
> 2.34.1
>