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 587FE28980F; Wed, 8 Apr 2026 18:31:23 +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=1775673083; cv=none; b=Uz1KXwnEouZbwJI2UrBH90hqXC2zK3U+HUoWklh+UIgqmWYlIW0u/mtCmeMw1SJRMJRr4VIH/VGQ2JIK7wpPi6rUmga3eguHwhXNR3/VJKzUTJlM+JxkazKwoZow+V7zMKfm1CayanikUJLQkWCQD91xKPXCwywqxrozartNajw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775673083; c=relaxed/simple; bh=E8OiE5dF73X3ghydFKMb0Sbhpmu7rFCpYmKBlmeXf8s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=s0GOdsWtrGEEdnRjnjU4jQAdy3gVNBl9w+G6HtR/aZjaWVIOKA59EIDg8MmK7n7gPyMoxwgiOIBiUvJEyU8NS91B9LhekMK/9gmOykAqrWns+z+zxkoVtAciCI2hEw3euSxHYO9JfZiVqNbZl5rK3yn15OBlYJRBz3aMIoWBh6c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=MtCjrJAO; 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="MtCjrJAO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E2532C2BCB0; Wed, 8 Apr 2026 18:31:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1775673083; bh=E8OiE5dF73X3ghydFKMb0Sbhpmu7rFCpYmKBlmeXf8s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MtCjrJAOuodrxPShvvNsSQjJkX5s5lpaedcDR0ysyO7HdFGmaJjt7pYyQOxVkmms9 67sDTlyRt4BAqWqELLijYUiHXO/MVmn5uH0yCjUOpJ2kGVcvVymF/Ho/9wQu8OGCQC EDSpOE8DWPCK3OYDqb9y9FGY9gQDHimQrASWAiVU= 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 6.18 094/277] net/x25: Fix potential double free of skb Date: Wed, 8 Apr 2026 20:01:19 +0200 Message-ID: <20260408175937.384236288@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260408175933.836769063@linuxfoundation.org> References: <20260408175933.836769063@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org 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: 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 b981a4828d08c..0dbc73efab1cb 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 (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