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=1794272631; b=q3SLUB1hc2MybMejjvUKKVUwNy9bSuPM7GOotlX7EaNYaET05kVwbtsSA3RrZ1C9Y5GE iCmtTe/x7+uO7Af91hHfGIg8OSeBtAhRr0mGMMtxpABJCKZCSsIMcD1zqvwM4cHM4jzLw wC88MFg4Uxs+kTp2C0nPlFRtYr+6kSzo2CHgOMp2N//vg1LimJk/tt8aH5VwW+m3PO3ke Ro1y+4s1kqdUXJZ+xhIpcQn7snPe8oCHapCxe5JvEUgMD9NKbshGBAqv91YZFfbQ6R0Ci szleNSAhTMupcOsxc1zJwHzqJEFRqVWxTyb/KDbTePgRYqlLZylJVLuvVSflClCTDcg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794272631; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=MgLbFow70R7PhThgWYH0pSeeA/OVp3v+JuuTdUrTk3U=; b=1W1OYLouMlVkERQ4HJKVultSJ9ePo5xNz8GEAV6jvFL3maPk5opF5YNWNLyPNiurvApv plCwOfx1DnDNujbSPj9FS03tzcv5vp5MJpZ+DiUtVQhgkwiyTU2VaQMQ8z90rt6iuqk+Z eIND27uO0R5T/c1xnCe4PLg7m+Gk+r+gfg8OAw+Af6TvSt2vtShWzlmenUhBgYbiw9V27 jpo5r+5klTSqox96VcO9qAvSpeRwfanoZtyuoZ43CGVsSLNCY40TfsmwxJ7zrCh7qT6ds SepHio1ocHHbhfmxI8rD+OSjm8kEN09RmSibBVZAxyP01XwtJ059iu0R40k/pBn5/kg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=O6dQ6ne5; 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 DC066606A31C for ; Tue, 10 Nov 2026 01:03:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=O6dQ6ne5 Received: by smtp.kernel.org (Postfix) with ESMTPSA id D82FB1F0089F; Tue, 10 Nov 2026 01:03:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794272630; bh=MgLbFow70R7PhThgWYH0pSeeA/OVp3v+JuuTdUrTk3U=; h=From:To:Cc:Subject:Date; b=O6dQ6ne5pWfibTv3FBMLFp3aTKYJy511ZT5ZXuJ0uY8I/24QZqwOomeEhw0P9RZfn esBPZh2dJpbwNOFI0T/VCY85kdWN+6JBbL0vLkHbeV0ju+Ob+rjhrfrh7LieIRytQ7 x3oTUbjVhuNPo6ztHOE9k/Rpa8nj34PKZN/8a78OhXNblIRsEIWHWC36ujxmJbGjVP 1TQd+IbmWegByb3vzRiZaWSEBtz6RpgadFwoeH/r4i4d2Ozj4V550mDOBQRjvvB2KO sRUx7JjwvgG4MKli56H1GBK9b2BtEk2YF733p8y28gOpjnFm1bBuiYDgTDvldV5NHk dO4TFFDhkUrtg== From: Sasha Levin To: edumazet@kernel.org, kylebot@openai.com, fw@strlen.de, idosch@nvidia.com, jiayuan.chen@linux.dev, wang.zhan@smartx.com, pabeni@redhat.com Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] inet: frags: limit the truesize of a reassembly queue" failed to apply to 6.18-stable tree Date: Mon, 9 Nov 2026 20:03:48 -0500 Message-ID: <20261109200348-failed-6.18-3ae20e4697eb@kernel.org> X-Mailer: git-send-email 2.53.0 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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y git checkout FETCH_HEAD git cherry-pick -x 3ae20e4697eb969104fe4b1e98a675f0100382b6 # git commit -s git send-email --to '' --in-reply-to '20261109200348-failed-6.18-3ae20e4697eb@kernel.org' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 3ae20e4697eb969104fe4b1e98a675f0100382b6 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 30 Oct 2026 09:12:25 +0100 Subject: [PATCH] inet: frags: limit the truesize of a reassembly queue 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 --- 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