From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 852B326CE32; Mon, 13 Apr 2026 16:36:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776098202; cv=none; b=d+OZeoNzIITsEMbyuj1igHU/ld+MzxQMBdaj2BVBKzyD5fpC4g9G1Bv1vi0/lViRzD16At81qhTgYmojXkgIfbUZ4by8qU7sVqJ1KOSNWPinLpE3TIq7JrrnOsQJxj9jbJAVIhlaYlPIrmYp554yL37+25BleaarzxSRKVBcyv8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776098202; c=relaxed/simple; bh=ziSnnaBw0OE0vLT+69HNofXMjqxKN0DN2AScYYmyxpY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TR40GhQ++IYZSnoh7sCeCDTUjhRjrUjZKwm/0GEjJZOzUXIl0Ce0ITzIS6I3te6iKplyewgMG+Dx6q8gEKLXhUyD2C2rT9SpYE8dg5CvcEz3hASy7uzgDjngj6gfNvpHYJ4PEKWmzy75Q9gKXhqKWHwe7uK1l7KgsuN/QqmR0Cs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FXwG2yIO; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="FXwG2yIO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1C6F7C2BCAF; Mon, 13 Apr 2026 16:36:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776098202; bh=ziSnnaBw0OE0vLT+69HNofXMjqxKN0DN2AScYYmyxpY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FXwG2yIOYQYHBSpLt7XSrHDDqOi76y8869uyIopSoiow/YswjFpSLOF/44EaK3RSE RSBe1YbDtSMybYNWnUCr3iFO448RJ2exVhMK3M2ETBBkxRZBR34veGhMiTJGOh8EVW FVXGcHxjhaPffjw3Dx+3NCBGiwKofeFnDHW8eFis= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Martin Schiller , Paolo Abeni , Sasha Levin Subject: [PATCH 5.15 432/570] net/x25: Fix potential double free of skb Date: Mon, 13 Apr 2026 17:59:23 +0200 Message-ID: <20260413155846.656298911@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260413155830.386096114@linuxfoundation.org> References: <20260413155830.386096114@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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Martin Schiller [ Upstream commit d10a26aa4d072320530e6968ef945c8c575edf61 ] When alloc_skb fails in x25_queue_rx_frame it calls kfree_skb(skb) at line 48 and returns 1 (error). This error propagates back through the call chain: x25_queue_rx_frame returns 1 | v x25_state3_machine receives the return value 1 and takes the else branch at line 278, setting queued=0 and returning 0 | v x25_process_rx_frame returns queued=0 | v x25_backlog_rcv at line 452 sees queued=0 and calls kfree_skb(skb) again This would free the same skb twice. Looking at x25_backlog_rcv: net/x25/x25_in.c:x25_backlog_rcv() { ... queued = x25_process_rx_frame(sk, skb); ... if (!queued) kfree_skb(skb); } Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Martin Schiller Link: https://patch.msgid.link/20260331-x25_fraglen-v4-1-3e69f18464b4@dev.tdt.de Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/x25/x25_in.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/net/x25/x25_in.c b/net/x25/x25_in.c index e1c4197af468e..77ad186507f64 100644 --- a/net/x25/x25_in.c +++ b/net/x25/x25_in.c @@ -44,10 +44,9 @@ static int x25_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more) if (!more && x25->fraglen > 0) { /* End of fragment */ int len = x25->fraglen + skb->len; - if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){ - kfree_skb(skb); + skbn = alloc_skb(len, GFP_ATOMIC); + if (!skbn) return 1; - } skb_queue_tail(&x25->fragment_queue, skb); -- 2.53.0