lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Thu, 30 Nov 2023 17:25:20 -0800
From: Jakub Kicinski <>
To: Kees Cook <>
Cc: kernel test robot <>, "David S. Miller"
 <>, Eric Dumazet <>, Paolo Abeni
 <>, Johannes Berg <>, Jeff
 Johnson <>, Michael Walle <>, Max
 Schulze <>,,,,
Subject: Re: [PATCH] netlink: Return unsigned value for nla_len()

On Thu, 30 Nov 2023 12:01:01 -0800 Kees Cook wrote:
> This has the additional benefit of being defensive in the face of nlattr
> corruption or logic errors (i.e. nla_len being set smaller than

As Johannes predicted I'd rather not :(

The callers should put the nlattr thru nla_ok() during validation
(nla_validate()), or walking (nla_for_each_* call nla_ok()).

> -static inline int nla_len(const struct nlattr *nla)
> +static inline u16 nla_len(const struct nlattr *nla)
>  {
> -	return nla->nla_len - NLA_HDRLEN;
> +	return nla->nla_len > NLA_HDRLEN ? nla->nla_len - NLA_HDRLEN : 0;
>  }

Note the the NLA_HDRLEN is the length of struct nlattr.
I mean of the @nla object that gets passed in as argument here.
So accepting that nla->nla_len may be < NLA_HDRLEN means
that we are okay with dereferencing a truncated object...

We can consider making the return unsinged without the condition maybe?
pw-bot: cr

Powered by blists - more mailing lists