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Tue, 14 Apr 2026 22:58:13 -0700 (PDT) Received: from TDC4045031631.e0cglfehwr0e5gttmepj3hi3hf.ux.internal.cloudapp.net ([20.63.37.123]) by smtp.gmail.com with ESMTPSA id 00721157ae682-7b768d387eesm4440177b3.29.2026.04.14.22.58.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Apr 2026 22:58:12 -0700 (PDT) From: Ashutosh Desai To: netdev@vger.kernel.org Cc: linux-hams@vger.kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, stable@vger.kernel.org, linux-kernel@vger.kernel.org, Ashutosh Desai Subject: [PATCH v3 net] rose: fix OOB reads on short CLEAR REQUEST frames Date: Wed, 15 Apr 2026 05:57:56 +0000 Message-Id: <20260415055756.3825584-1-ashutoshdesai993@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit rose_process_rx_frame() calls rose_decode() which reads skb->data[2] without any prior length check. For CLEAR REQUEST frames the state machines then read skb->data[3] and skb->data[4] as the cause and diagnostic bytes. A crafted 3-byte ROSE CLEAR REQUEST frame passes the minimum length gate in rose_route_frame() and reaches rose_process_rx_frame(), where rose_decode() reads one byte past the header and the state machines read two bytes past the valid buffer. A remote peer can exploit this to leak kernel memory contents or trigger a kernel panic. Add a pskb_may_pull(skb, 3) check before rose_decode() to cover its skb->data[2] access, and a pskb_may_pull(skb, 5) check afterwards for the CLEAR REQUEST path to cover the cause and diagnostic reads. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Ashutosh Desai --- V2 -> V3: drop kfree_skb() calls to fix double-free; add end-user visible symptom to commit log; use [net] subject prefix V1 -> V2: switch skb->len check to pskb_may_pull; add pskb_may_pull(skb, 3) before rose_decode() to cover its skb->data[2] access v2: https://lore.kernel.org/netdev/177614667427.3606651.8700070406932922261@gmail.com/ v1: https://lore.kernel.org/netdev/20260409013246.2051746-1-ashutoshdesai993@gmail.com/ net/rose/rose_in.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/rose/rose_in.c b/net/rose/rose_in.c index 0276b393f0e5..8e60dc562b4a 100644 --- a/net/rose/rose_in.c +++ b/net/rose/rose_in.c @@ -269,8 +269,14 @@ int rose_process_rx_frame(struct sock *sk, struct sk_buff *skb) if (rose->state == ROSE_STATE_0) return 0; + if (!pskb_may_pull(skb, 3)) + return 0; + frametype = rose_decode(skb, &ns, &nr, &q, &d, &m); + if (frametype == ROSE_CLEAR_REQUEST && !pskb_may_pull(skb, 5)) + return 0; + switch (rose->state) { case ROSE_STATE_1: queued = rose_state1_machine(sk, skb, frametype); -- 2.34.1