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Mon, 13 May 2024 22:49:56 -0700 (PDT) Received: from www.outflux.net ([198.0.35.241]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-6f4d2ae0f7fsm8289079b3a.120.2024.05.13.22.49.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 May 2024 22:49:55 -0700 (PDT) Date: Mon, 13 May 2024 22:49:54 -0700 From: Kees Cook To: Sam James Cc: chunkeey@gmail.com, chunkeey@googlemail.com, davem@davemloft.net, edumazet@google.com, helmut.schaa@googlemail.com, johannes@sipsolutions.net, kernel@quicinc.com, kuba@kernel.org, kvalo@kernel.org, linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, pabeni@redhat.com, pkshih@realtek.com, quic_jjohnson@quicinc.com, stf_xl@wp.pl, toke@toke.dk Subject: Re: [PATCH v2 2/2] mac80211: Use flexible array in struct ieee80211_tim_ie Message-ID: <202405132245.017023A@keescook> References: <202308301529.AC90A9EF98@keescook> <87jzjxgfnt.fsf@gentoo.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87jzjxgfnt.fsf@gentoo.org> On Tue, May 14, 2024 at 05:51:02AM +0100, Sam James wrote: > I think I've just hit this, unless it's been fixed since and it's just > similar. > > ``` > [ 291.051876] ================================================================================ > [ 291.051892] UBSAN: array-index-out-of-bounds in /var/tmp/portage/sys-kernel/gentoo-kernel-6.6.30/work/linux-6.6/include/linux/ieee80211.h:4455:28 > [ 291.051901] index 1 is out of range for type 'u8 [1]' > [ 291.051908] CPU: 2 PID: 627 Comm: kworker/2:3 Not tainted 6.6.30-gentoo-dist-hardened #1 > [ 291.051917] Hardware name: ASUSTeK COMPUTER INC. UX305FA/UX305FA, BIOS UX305FA.216 04/17/2019 > [ 291.051922] Workqueue: events cfg80211_wiphy_work [cfg80211] > [ 291.052082] Call Trace: > [ 291.052088] > [ 291.052096] dump_stack_lvl (lib/dump_stack.c:107) > [ 291.052114] __ubsan_handle_out_of_bounds (lib/ubsan.c:218 (discriminator 1) lib/ubsan.c:348 (discriminator 1)) > [ 291.052130] ieee80211_rx_mgmt_beacon (include/linux/ieee80211.h:4455 net/mac80211/mlme.c:6047) mac80211 This looks like it's this line in ieee80211_rx_mgmt_beacon(): ieee80211_check_tim(elems->tim, elems->tim_len, vif_cfg->aid)) { which is: static inline bool ieee80211_check_tim(const struct ieee80211_tim_ie *tim, u8 tim_len, u16 aid) { ... return !!(tim->virtual_map[index] & mask); ^^^^^^^^^^^^^^^^^^^^^^^ } UBSAN says it's because the array is defined as "virtual_map[1]": struct ieee80211_tim_ie { u8 dtim_count; u8 dtim_period; u8 bitmap_ctrl; /* variable size: 1 - 251 bytes */ u8 virtual_map[1]; } __packed; This was fixed in commit 2ae5c9248e06 ("wifi: mac80211: Use flexible array in struct ieee80211_tim_ie") which was part of the v6.7 release. > (It was a fun mini-adventure to get the trace usable and I should send > some patches to decode_stacktrace.sh, I think...) Please do! :) -- Kees Cook