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 EEFA23FADF1; Thu, 30 Jul 2026 14:59:00 +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=1785423542; cv=none; b=N77KqLGpFFO2tmGPKAWaGQxSAdE9Tb+H3/SwM/KEfVHIZL5Md4+MtukNH0YOl6AhAcDjJL3a8CyESNnvG9oWSP+b2eoC99rKTkdqpiWXxrvvuGOnNmcsclqQDa4lqx0MCoCklUPRkiuGpKBnO7GLJxfytKSzSQnsC8T1vfG4r34= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785423542; c=relaxed/simple; bh=HgdlQZFxq4dUJFhkGIlYbqRNE+kUlYKmk8k3HXYD7fQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eAwUYoD8Dq0Rwl5ctsxevVmWsL5Ljlrx4yNUvWK+As6QVSb0JVgohLqpvSm5v243Lk5Y12OGY0fFL/Bt4N4QE+KjbmXwD3gY+suyITT9oM1gAwDU8HKSjobXIvTIQXSxQQu3pLx6NnLWmFTTrbLF/qW1LSsyFaV6jSdQgQjYWGo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Wct+qCIB; 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="Wct+qCIB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EDD641F000E9; Thu, 30 Jul 2026 14:58:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785423540; bh=ub60jUoYboG0gkLIcgsR0ZUIEcI00MYKWgxwsX8mr6Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Wct+qCIB9B5HS/Byb1ylqMtFr2x1VDELUJpUlmYgBbyfwI18nz8b0qHkGAz1GLkNN 5mK8/6Ctcm/s4mj8FsEea1Cx7DRuPNgKyuyQMds2syofavKxtWa6g4k3zeBFeH4Ryj B1WqCdP6UYqE6bZ7MHtPxzpFjW7mWhjWKRlFsgR0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Petr Wozniak , Steffen Klassert , Sasha Levin Subject: [PATCH 6.18 036/675] xfrm: fix stale skb->prev after async crypto steals a GSO segment Date: Thu, 30 Jul 2026 16:06:06 +0200 Message-ID: <20260730141445.886637133@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141445.110192266@linuxfoundation.org> References: <20260730141445.110192266@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Petr Wozniak [ Upstream commit 3f4c3919baf0944ad96580467c302bc6c7758b00 ] skb_gso_segment() leaves the segment list head with ->prev pointing at the last segment, an invariant validate_xmit_skb_list() relies on when it sets its tail pointer (tail = skb->prev). When validate_xmit_xfrm() walks a GSO list and some segments are stolen by async crypto (->xmit() returns -EINPROGRESS), those segments are unlinked from the list but the head ->prev is never updated. If the last segment is the one stolen, the returned head still has ->prev pointing at it, even though it is now owned by the crypto engine and may be freed. validate_xmit_skb_list() later does tail->next = skb, writing through that stale pointer -- a use-after-free. Repoint skb->prev at the last retained segment before returning. Fixes: f53c723902d1 ("net: Add asynchronous callbacks for xfrm on layer 2.") Signed-off-by: Petr Wozniak Signed-off-by: Steffen Klassert Signed-off-by: Sasha Levin --- net/xfrm/xfrm_device.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/net/xfrm/xfrm_device.c b/net/xfrm/xfrm_device.c index 8b526e3676389a..4719aba331cd66 100644 --- a/net/xfrm/xfrm_device.c +++ b/net/xfrm/xfrm_device.c @@ -224,6 +224,14 @@ struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t featur pskb = skb2; } + /* skb_gso_segment() set skb->prev to the last segment, but async + * crypto may have stolen it above without updating ->prev. Repoint + * it at the last retained segment so validate_xmit_skb_list() does + * not chain onto a segment now owned by the crypto engine. + */ + if (skb) + skb->prev = pskb; + return skb ? skb : ERR_PTR(-EINPROGRESS); } EXPORT_SYMBOL_GPL(validate_xmit_xfrm); -- 2.53.0