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Message-ID: <1d3a2fafcc14de7406fd689029277fd74ed3ce87.camel@sipsolutions.net>
Date: Tue, 22 Nov 2022 17:46:09 +0100
From: Johannes Berg <johannes@...solutions.net>
To: Kees Cook <keescook@...omium.org>
Cc: Luca Coelho <luciano.coelho@...el.com>,
Haim Dreyfuss <haim.dreyfuss@...el.com>,
Miri Korenblit <miriam.rachel.korenblit@...el.com>,
Petr Stourac <pstourac@...hat.com>,
linux-kernel@...r.kernel.org,
Mordechay Goodstein <mordechay.goodstein@...el.com>,
Jakub Kicinski <kuba@...nel.org>,
Eric Dumazet <edumazet@...gle.com>,
Nathan Errera <nathan.errera@...el.com>,
Paolo Abeni <pabeni@...hat.com>,
Shaul Triebitz <shaul.triebitz@...el.com>,
netdev@...r.kernel.org,
Gregory Greenman <gregory.greenman@...el.com>,
Abhishek Naik <abhishek.naik@...el.com>,
Jose Ignacio Tornos Martinez <jtornosm@...hat.com>,
Ayala Beker <ayala.beker@...el.com>,
"David S. Miller" <davem@...emloft.net>,
linux-wireless@...r.kernel.org,
Sriram R <quic_srirrama@...cinc.com>,
Kalle Valo <kvalo@...nel.org>,
Mike Golant <michael.golant@...el.com>,
Emmanuel Grumbach <emmanuel.grumbach@...el.com>,
"Gustavo A. R. Silva" <gustavo@...eddedor.com>,
linux-next@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: Coverity: iwl_mvm_sec_key_add(): Memory - corruptions
On Fri, 2022-11-18 at 14:25 -0800, Kees Cook wrote:
> On Fri, Nov 18, 2022 at 10:04:38PM +0100, Johannes Berg wrote:
> > On Fri, 2022-11-18 at 08:54 -0800, coverity-bot wrote:
> > >
> > > *** CID 1527370: Memory - corruptions (OVERRUN)
> > > drivers/net/wireless/intel/iwlwifi/mvm/mld-key.c:123 in iwl_mvm_sec_key_add()
> > > 117
> > > 118 if (WARN_ON(keyconf->keylen > sizeof(cmd.u.add.key)))
> > > 119 return -EINVAL;
> > > 120
> > > 121 if (keyconf->cipher == WLAN_CIPHER_SUITE_WEP40 ||
> > > 122 keyconf->cipher == WLAN_CIPHER_SUITE_WEP104)
> > > vvv CID 1527370: Memory - corruptions (OVERRUN)
> > > vvv Overrunning buffer pointed to by "cmd.u.add.key + 3" of 32 bytes by passing it to a function which accesses it at byte offset 34 using argument "keyconf->keylen" (which evaluates to 32). [Note: The source code implementation of the function has been overridden by a builtin model.]
> > > 123 memcpy(cmd.u.add.key + IWL_SEC_WEP_KEY_OFFSET, keyconf->key,
> > > 124 keyconf->keylen);
> > > 125 else
> > > 126 memcpy(cmd.u.add.key, keyconf->key, keyconf->keylen);
> > > 127
> > > 128 if (keyconf->cipher == WLAN_CIPHER_SUITE_TKIP) {
> > >
> > > If this is a false positive, please let us know so we can mark it as
> > > such, or teach the Coverity rules to be smarter. If not, please make
> > > sure fixes get into linux-next. :) For patches fixing this, please
> > > include these lines (but double-check the "Fixes" first):
> > >
> >
> > Well, I don't think you can teach coverity this easily, but the
> > WARN_ON() check there is not really meant to protect this - WEP keys
> > must have a length of either 5 or 13 bytes (40 or 104 bits!).
> >
> > So there's no issue here, but I'm not surprised that coverity wouldn't
> > be able to figure that out through the stack.
>
> Gotcha. And some other layer is doing the verification that cipher and
> keylen are correctly matched?
Yes, the key must come through cfg80211_validate_key_settings() at some
point.
johannes
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