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Mon, 24 Nov 2025 05:55:26 -0800 (PST) Received: from gmail.com ([183.56.183.11]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-29b5b25e56esm138338545ad.57.2025.11.24.05.55.23 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 24 Nov 2025 05:55:26 -0800 (PST) From: jiefeng.z.zhang@gmail.com To: netdev@vger.kernel.org Cc: kuba@kernel.org, davem@davemloft.net, pabeni@redhat.com, andrew+netdev@lunn.ch, edumazet@google.com, linux-kernel@vger.kernel.org, irusskikh@marvell.com, Jiefeng Zhang Subject: [PATCH net v3] net: atlantic: fix fragment overflow handling in RX path Date: Mon, 24 Nov 2025 21:55:18 +0800 Message-Id: <20251124135518.66243-1-jiefeng.z.zhang@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Jiefeng Zhang The atlantic driver can receive packets with more than MAX_SKB_FRAGS (17) fragments when handling large multi-descriptor packets. This causes an out-of-bounds write in skb_add_rx_frag_netmem() leading to kernel panic. The issue occurs because the driver doesn't check the total number of fragments before calling skb_add_rx_frag(). When a packet requires more than MAX_SKB_FRAGS fragments, the fragment index exceeds the array bounds. Fix by assuming there will be an extra frag if buff->len > AQ_CFG_RX_HDR_SI= ZE, then all fragments are accounted for. And reusing the existing check to prevent the overflow earlier in the code path. This crash occurred in production with an Aquantia AQC113 10G NIC. Stack trace from production environment: ``` RIP: 0010:skb_add_rx_frag_netmem+0x29/0xd0 Code: 90 f3 0f 1e fa 0f 1f 44 00 00 48 89 f8 41 89 ca 48 89 d7 48 63 ce 8b 90 c0 00 00 00 48 c1 e1 04 48 01 ca 48 03 90 c8 00 00 00 <48> 89 7a 30 44 89 52 3c 44 89 42 38 40 f6 c7 01 75 74 48 89 fa 83 RSP: 0018:ffffa9bec02a8d50 EFLAGS: 00010287 RAX: ffff925b22e80a00 RBX: ffff925ad38d2700 RCX: fffffffe0a0c8000 RDX: ffff9258ea95bac0 RSI: ffff925ae0a0c800 RDI: 0000000000037a40 RBP: 0000000000000024 R08: 0000000000000000 R09: 0000000000000021 R10: 0000000000000848 R11: 0000000000000000 R12: ffffa9bec02a8e24 R13: ffff925ad8615570 R14: 0000000000000000 R15: ffff925b22e80a00 FS: 0000000000000000(0000) GS:ffff925e47880000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff9258ea95baf0 CR3: 0000000166022004 CR4: 0000000000f72ef0 PKRU: 55555554 Call Trace: aq_ring_rx_clean+0x175/0xe60 [atlantic] ? aq_ring_rx_clean+0x14d/0xe60 [atlantic] ? aq_ring_tx_clean+0xdf/0x190 [atlantic] ? kmem_cache_free+0x348/0x450 ? aq_vec_poll+0x81/0x1d0 [atlantic] ? __napi_poll+0x28/0x1c0 ? net_rx_action+0x337/0x420 ``` Changes in v3: - Fix by assuming there will be an extra frag if buff->len > AQ_CFG_RX_HDR_= SIZE, then all fragments are accounted for. Signed-off-by: Jiefeng Zhang --- drivers/net/ethernet/aquantia/atlantic/aq_ring.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c b/drivers/net= /ethernet/aquantia/atlantic/aq_ring.c index f21de0c21e52..d23d23bed39f 100644 --- a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c +++ b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c @@ -547,6 +547,11 @@ static int __aq_ring_rx_clean(struct aq_ring_s *self, = struct napi_struct *napi, =20 if (!buff->is_eop) { unsigned int frag_cnt =3D 0U; + + /* There will be an extra fragment */ + if (buff->len > AQ_CFG_RX_HDR_SIZE) + frag_cnt++; + buff_ =3D buff; do { bool is_rsc_completed =3D true; --=20 2.39.5