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Tue, 30 Jun 2026 09:47:03 -0700 (PDT) X-Received: by 2002:a05:6a00:92a5:b0:847:8337:64e4 with SMTP id d2e1a72fcca58-8479f1f553amr3418980b3a.30.1782838022460; Tue, 30 Jun 2026 09:47:02 -0700 (PDT) Received: from kernel-devel.tail62cea.ts.net ([240d:1a:c0d:9f00:be24:11ff:fe35:71b3]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-847a03b9ffasm2378390b3a.59.2026.06.30.09.47.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Jun 2026 09:47:01 -0700 (PDT) From: Shigeru Yoshida To: Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Matvey Kovalev , Shigeru Yoshida , Pavel Zhigulin , Jamie Bainbridge Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net] qede: fix off-by-one in BD ring consumption on build_skb failure Date: Wed, 1 Jul 2026 01:46:20 +0900 Message-ID: <20260630164623.3152625-1-syoshida@redhat.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit qede_rx_build_skb() and qede_tpa_rx_build_skb() do not check for a NULL return from qede_build_skb(). When it returns NULL under memory pressure, the functions still consume a BD from the ring before returning NULL. The callers then recycle additional BDs, resulting in one extra BD being consumed (off-by-one). This desynchronizes the BD ring, which can corrupt DMA page reference counts and lead to SLUB freelist corruption. Commit 4e910dbe3650 ("qede: confirm skb is allocated before using") added a NULL check inside qede_build_skb() to prevent a NULL pointer dereference, but did not address the missing NULL checks in the callers, making this off-by-one reachable. Fix this by adding NULL checks for the return value of qede_build_skb() in both qede_rx_build_skb() and qede_tpa_rx_build_skb(), returning NULL immediately before any BD ring manipulation. Fixes: 4e910dbe3650 ("qede: confirm skb is allocated before using") Signed-off-by: Shigeru Yoshida --- drivers/net/ethernet/qlogic/qede/qede_fp.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/net/ethernet/qlogic/qede/qede_fp.c b/drivers/net/ethernet/qlogic/qede/qede_fp.c index 33e18bb69774..c11e0d8f98aa 100644 --- a/drivers/net/ethernet/qlogic/qede/qede_fp.c +++ b/drivers/net/ethernet/qlogic/qede/qede_fp.c @@ -765,6 +765,9 @@ qede_tpa_rx_build_skb(struct qede_dev *edev, struct sk_buff *skb; skb = qede_build_skb(rxq, bd, len, pad); + if (unlikely(!skb)) + return NULL; + bd->page_offset += rxq->rx_buf_seg_size; if (bd->page_offset == PAGE_SIZE) { @@ -812,6 +815,8 @@ qede_rx_build_skb(struct qede_dev *edev, } skb = qede_build_skb(rxq, bd, len, pad); + if (unlikely(!skb)) + return NULL; if (unlikely(qede_realloc_rx_buffer(rxq, bd))) { /* Incr page ref count to reuse on allocation failure so -- 2.54.0