From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C33B94C8C7F for ; Sun, 18 Oct 2026 16:21:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792340496; cv=none; b=sMkLySwtxM36LeTONYvvYW2e3Qdnz11xyYD37H2vLvCIfBobeMJQ2AOowBX8h03YfRPDhMLpJfStwHL+mE/sQo2Yyeph0cEMJUNNIv6ENJY0dDaTL+m5O6FEMdc4nt6lj6pL44edudvGACk3p/4PYIEsFGYbuRH0zKSeioI9NM0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792340496; c=relaxed/simple; bh=Aw+2RY9uFg9V8v/xZoj2GGDSAAyHJF9ZEXZDf/lOixQ=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=SRsQqCiBSfjzUEdVP2xPEvhPLkeHeFrqRLYvQEh+7Z+878uPmZLfcNWpUaQliJuYqUuo7R4Be1BSGCkNGWDVnChiB6C8URdyG3jLpRHCms7ob55NfrCPPS75/NYmwD8LOuIJhgxv5xqQc3dUl01wXA5fleSnriK/k7CLJQEb74U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=R6rEXFXP; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="R6rEXFXP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A61CA1F000C4; Sun, 18 Oct 2026 16:21:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792340495; bh=BNxMseoZI4Hi+odgn82VnZF15IZKpHgfNq5HabzbR5Q=; h=From:To:Cc:Subject:Date:Reply-To; b=R6rEXFXPRVyjV5Gz1uqSsHGpR1DgEv4O7fUTB2Xg09/fH5VDpoGCFcjgj+JtA9kP8 8LaEymJ3rZCBX9WYc4Wae3LW5Psp56PNkv9/FG+3cxgQ619nXKDRaIr2dsAfXKN4oG h4S5uGdr2UnSJX1A/xArWs4h2uSJKwbbPDYEdpEI= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-98829: wifi: mac80211: drop oversized fragments to avoid extra_len overflow Date: Sun, 18 Oct 2026 17:46:44 +0200 Message-ID: <2026101830-CVE-2026-98829-7bdd@gregkh> X-Mailer: git-send-email 2.56.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=4169; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=COAar4aS8SYV0uOOxlKcOXtn/xYA+DKZF1KbljNOf44=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlXXsZduXHBhN07oNdm9fbf/FzfK7eUbGfc/tKnvvO7w cFKXV/mjlgWBkEmBlkxRZYv23iO7q84pOhlaHsaZg4rE8gQBi5OAZhIwgyGeQqHz/W7N78wWJnu aS4nseREeFKHDcOCi+cZCjKEmaQfbZIrPLD1WmnUP9Y9AA== X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: drop oversized fragments to avoid extra_len overflow In ieee80211_rx_h_defragment(), fragment payloads are accumulated into entry->extra_len as subsequent fragments arrive: entry->extra_len += rx->skb->len; When the final fragment arrives, the head fragment is dequeued, and pskb_expand_head() is called with entry->extra_len to ensure sufficient tailroom for all queued fragments before copying: if (skb_tailroom(rx->skb) < entry->extra_len) { if (unlikely(pskb_expand_head(rx->skb, 0, entry->extra_len, GFP_ATOMIC))) { ... } } while ((skb = __skb_dequeue(&entry->skb_list))) { skb_put_data(rx->skb, skb->data, skb->len); dev_kfree_skb(skb); } In commit 69f132236827 ("mac80211: shrink struct ieee80211_fragment_entry"), entry->extra_len was narrowed from unsigned int to u16 in order to reduce structure memory footprint. However, an IEEE 802.11 frame sequence can contain up to 16 fragments (frag numbers 0..15). If a sequence of large fragments arrives (e.g. from a malicious peer or rogue AP), the sum of fragment lengths can exceed 65535 bytes (for example, 15 fragments of 4400 bytes total 66000 bytes). Because extra_len is a u16, this addition overflows and wraps around modulo 65536 (e.g. 66000 wraps to 464). Consequently, pskb_expand_head() allocates only the truncated amount of tailroom (or is skipped entirely if the head fragment already has >= 464 bytes of tailroom). When skb_put_data() subsequently iterates through the queued skb list, it appends the full payload into the undersized buffer, causing skb_put() to trigger skb_over_panic() and crash the kernel in softirq context. A legitimate MSDU in IEEE 802.11 is at most 2304 bytes (or up to 7935/11454 bytes for A-MSDU, which is not fragmented), well below U16_MAX. Fix this without increasing the size of struct ieee80211_fragment_entry by checking whether adding the incoming fragment length would exceed U16_MAX. If so, purge the queued fragments and drop the frame. [assign a separate drop reason] The Linux kernel CVE team has assigned CVE-2026-98829 to this issue. Affected and fixed versions =========================== Issue introduced in 4.3 with commit 69f132236827ce7d4531846cc2b9447dd5620aff and fixed in 6.18.56 with commit 9338b2dea74cb0fc80a4c958b68e687610ba2261 Issue introduced in 4.3 with commit 69f132236827ce7d4531846cc2b9447dd5620aff and fixed in 7.2.10 with commit 870b8cb9baa9bd859deceb33ae158011e6ba2360 Issue introduced in 4.3 with commit 69f132236827ce7d4531846cc2b9447dd5620aff and fixed in 7.3-rc6 with commit 5e4f3509793b4db2c0835340224743db680e861f Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-98829 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: net/mac80211/drop.h net/mac80211/rx.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/9338b2dea74cb0fc80a4c958b68e687610ba2261 https://git.kernel.org/stable/c/870b8cb9baa9bd859deceb33ae158011e6ba2360 https://git.kernel.org/stable/c/5e4f3509793b4db2c0835340224743db680e861f