From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794585580; b=FTDWZw7wxCwtWUc+/VGUKEGnwPecLAGuzGpVQYTxBIz6argvMAorJdcFWBr78W/6yNNx N1j/5hzJ4tObg0O2lJIk1IGY+peKi+1cYvDEvedkdNTRUcUjsrQUfAgNOxFGhAx/IFFkC OxBON1JFGVOI/zgBvxN6/Ly7bP1H/Kmjkfg17yo3IB6c9S2sk5EpwDi282Z8KwyWL8wdb E9VmiGz7zjLgKRV3PRcmF7Rf09P9ZThdFSYCuDeItXiObXDrCNAYmNxlKUMqAkxnCBPk5 PbYLUJEJejO3F87COYAyCQCS9KeYh0t3yUpahpfi8sYFULHRHTqRvyQAuJFAJ4K9bUg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794585580; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=5HZZkmi4P/xb0J36uD7JMHURy1B3/w6f7mQAIlUEBWs=; b=epkcDnecP2oOV2JLGbD7OsGJzH3PHJ/StzmQMwTgPDpe17D3Fjn+VgA0BoQ3jaIMIPBG YztNp7cGL3nQ/B7pgPglbnd4L2QcO+y11dyh9sVyJloUV4jq7ePVyJT5TwnSinyxr76G0 pTpEa8l5TYmfD+EimIZb42nFvH5Lil7/iP4BUHu3ga9sA7pOQWi01NfarWi48Z1S02Q/7 Ct8UNYZw6q42ZUxDwOsNKUH3L4bPVlZ1Aaihpsoki2kQgzUfl50/RqldDKJqiPhsTg7TD xCoU9qsFycQJOBU2je23iDQ3VOrwhgz6i6mYcrY6OONUhOVnVaeDyGZt3net+HgWXeA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=PDJREg2Q; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8CD71606EA9E; Fri, 13 Nov 2026 15:59:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=PDJREg2Q Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F6F41F000C4; Fri, 13 Nov 2026 15:59:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794585580; bh=5HZZkmi4P/xb0J36uD7JMHURy1B3/w6f7mQAIlUEBWs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=PDJREg2Qn/GdYFgk+hUNWG0YjrPEThWuQsQ58sNmDlxC6gj4lVnLDmie+otsvl5p+ shvd8pFXdz8DOgLwTPKU805bUihXz9aKbCtaoiv9Gso8641sG6S5VpEV4Bj4qARrCM KN1w1/5vXA+asxHScccSZi5vehd1sjaYSoEjOVKs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kyle Zeng , Florian Westphal , Eric Dumazet , Ido Schimmel , Jiayuan Chen , Wang Zhan , Paolo Abeni , Sasha Levin Subject: [PATCH 7.3 212/507] inet: frags: limit the truesize of a reassembly queue Date: Fri, 13 Nov 2026 10:48:36 -0500 Message-ID: <20261113153801.671672012@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261113153753.358973689@linuxfoundation.org> References: <20261113153753.358973689@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 3ae20e4697eb969104fe4b1e98a675f0100382b6 ] The truesize of fragments in a reassembly queue is only bounded by the per netns ipfrag_high_thresh sysctl, which has no upper limit. inet_frag_reasm_finish() sums the truesize of all fragments in an int. If this sum reaches 2^32, it wraps, and the final sk_wmem_alloc adjustment of the socket owning the reassembled skb can cancel its own reference, leading to a use-after-free of this socket. This can be triggered from an unprivileged user/network namespace, raising ipfrag_high_thresh and using padded TUN packets, which keep a large truesize after being trimmed by ip_rcv_core(). Track the sum of the truesize of fragments in each queue, and refuse a fragment that would make it bigger than INT_MAX / 2. Callers kill the queue on this error. This bound is far above the needs of legitimate traffic. Fixes: 18685451fc4e ("inet: inet_defrag: prevent sk release while still in use") Cc: stable@vger.kernel.org Reported-by: Kyle Zeng Cc: Florian Westphal Signed-off-by: Eric Dumazet Reviewed-by: Ido Schimmel Reviewed-by: Jiayuan Chen Tested-by: Wang Zhan Link: https://patch.msgid.link/20261030081225.2575462-1-edumazet@kernel.org Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- include/net/inet_frag.h | 9 +++++++++ net/ipv4/inet_fragment.c | 5 +++++ 2 files changed, 14 insertions(+) diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h index b02d2472b003e..c1fb419a9cf03 100644 --- a/include/net/inet_frag.h +++ b/include/net/inet_frag.h @@ -79,6 +79,7 @@ struct frag_v6_compare_key { * @tstamp_type: stamp has a mono delivery time (EDT) * @flags: fragment queue flags * @max_size: maximum received fragment size + * @truesize: sum of the truesize of queued fragments * @fqdir: pointer to struct fqdir * @rcu: rcu head for freeing deferall */ @@ -100,6 +101,7 @@ struct inet_frag_queue { u8 tstamp_type; __u8 flags; u16 max_size; + unsigned int truesize; struct fqdir *fqdir; struct rcu_head rcu; }; @@ -172,6 +174,13 @@ extern const u8 ip_frag_ecn_table[16]; #define IPFRAG_DUP 1 #define IPFRAG_OVERLAP 2 #define IPFRAG_MIXED_SECPATH 3 +#define IPFRAG_TOOBIG 4 + +/* Max sum of the truesize of fragments in a queue. This keeps the sums + * done in inet_frag_reasm_prepare() and inet_frag_reasm_finish() well + * below INT_MAX. Legitimate traffic stays far below this limit. + */ +#define INET_FRAG_MAX_TRUESIZE (INT_MAX / 2) int inet_frag_queue_insert(struct inet_frag_queue *q, struct sk_buff *skb, int offset, int end); void *inet_frag_reasm_prepare(struct inet_frag_queue *q, struct sk_buff *skb, diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c index c18da91c1f031..0b8d22ffafca6 100644 --- a/net/ipv4/inet_fragment.c +++ b/net/ipv4/inet_fragment.c @@ -336,6 +336,7 @@ void inet_frag_queue_flush(struct inet_frag_queue *q, q->rb_fragments = RB_ROOT; q->fragments_tail = NULL; q->last_run_head = NULL; + q->truesize = 0; } EXPORT_SYMBOL(inet_frag_queue_flush); @@ -446,6 +447,9 @@ int inet_frag_queue_insert(struct inet_frag_queue *q, struct sk_buff *skb, if (last && !secpath_equal(last, skb)) return IPFRAG_MIXED_SECPATH; + if (skb->truesize > INET_FRAG_MAX_TRUESIZE - q->truesize) + return IPFRAG_TOOBIG; + /* An IP fragment is never a GSO packet, but an untrusted source * (virtio_net_hdr) may have attached GSO metadata to it. Do not let * that reach the reassembled skb, whose head keeps the first @@ -510,6 +514,7 @@ int inet_frag_queue_insert(struct inet_frag_queue *q, struct sk_buff *skb, if (offset) nf_reset_ct(skb); + q->truesize += skb->truesize; return IPFRAG_OK; } EXPORT_SYMBOL(inet_frag_queue_insert); -- 2.53.0