lists.openwall.net   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-next>] [day] [month] [year] [list]
Message-Id: <20231206205904.make.018-kees@kernel.org>
Date:   Wed,  6 Dec 2023 12:59:07 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Kees Cook <keescook@...omium.org>,
        kernel test robot <lkp@...el.com>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Johannes Berg <johannes@...solutions.net>,
        Jeff Johnson <quic_jjohnson@...cinc.com>,
        Michael Walle <mwalle@...nel.org>,
        Max Schulze <max.schulze@...ine.de>, netdev@...r.kernel.org,
        linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org
Subject: [PATCH v3] netlink: Return unsigned value for nla_len()

The return value from nla_len() is never expected to be negative, and can
never be more than struct nlattr::nla_len (a u16). Adjust the prototype
on the function. This will let GCC's value range optimization passes
know that the return can never be negative, and can never be larger than
u16. As recently discussed[1], this silences the following warning in
GCC 12+:

net/wireless/nl80211.c: In function 'nl80211_set_cqm_rssi.isra':
net/wireless/nl80211.c:12892:17: warning: 'memcpy' specified bound 18446744073709551615 exceeds maximum object size 9223372036854775807 [-Wstringop-overflow=]
12892 |                 memcpy(cqm_config->rssi_thresholds, thresholds,
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
12893 |                        flex_array_size(cqm_config, rssi_thresholds,
      |                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
12894 |                                        n_thresholds));
      |                                        ~~~~~~~~~~~~~~

A future change would be to clamp the subtraction to make sure it never
wraps around if nla_len is somehow less than NLA_HDRLEN, which would
have the additional benefit of being defensive in the face of nlattr
corruption or logic errors.

Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311090752.hWcJWAHL-lkp@intel.com/ [1]
Cc: Jakub Kicinski <kuba@...nel.org>
Cc: David S. Miller <davem@...emloft.net>
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: Paolo Abeni <pabeni@...hat.com>
Cc: Johannes Berg <johannes@...solutions.net>
Cc: Jeff Johnson <quic_jjohnson@...cinc.com>
Cc: Michael Walle <mwalle@...nel.org>
Cc: Max Schulze <max.schulze@...ine.de>
Cc: netdev@...r.kernel.org
Cc: linux-wireless@...r.kernel.org
Link: https://lore.kernel.org/r/20231202202539.it.704-kees@kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 v3: do not cast NLA_HDRLEN to u16 (nicolas.dichtel)
 v2: https://lore.kernel.org/all/20231202202539.it.704-kees@kernel.org/
 v1: https://lore.kernel.org/all/20231130200058.work.520-kees@kernel.org/
---
 include/net/netlink.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/netlink.h b/include/net/netlink.h
index 83bdf787aeee..7678a596a86b 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -1200,7 +1200,7 @@ static inline void *nla_data(const struct nlattr *nla)
  * nla_len - length of payload
  * @nla: netlink attribute
  */
-static inline int nla_len(const struct nlattr *nla)
+static inline u16 nla_len(const struct nlattr *nla)
 {
 	return nla->nla_len - NLA_HDRLEN;
 }
-- 
2.34.1

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ