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Tue, 03 Nov 2026 00:31:46 -0800 (PST) Received: from spiderman.taila3fd8c.ts.net ([202.112.47.77]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3b07c5adc33sm3256364a91.1.2026.11.03.00.31.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Nov 2026 00:31:45 -0800 (PST) From: Li Ximo To: Laurent Pinchart , Vinod Koul Cc: Michal Simek , Frank Li , dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Wang Haoran , Li Ximo Subject: [PATCH v2] dmaengine: xilinx: dpdma: fix crash on zero-length cyclic transfer Date: Tue, 3 Nov 2026 16:31:32 +0800 Message-Id: <20261103083132.1122990-1-lixicaicai@gmail.com> X-Mailer: git-send-email 2.25.1 X-Mailing-List: linux-kernel@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 From: Wang Haoran When buf_len is zero, the descriptor build loop never runs, leaving the descriptor list empty. The following list_first_entry() on the empty list returns a bad pointer and causes a kernel oops. Return NULL if the descriptor list is empty after the loop. This issue was found by static analysis. Reported-by: Wang Haoran Reported-by: Li Ximo Signed-off-by: Wang Haoran --- v1: https://lore.kernel.org/r/20261023065900.3455414-1-lixicaicai@gmail.com v2: rewrite the commit message in simpler words as suggested by Frank Li; no code change. drivers/dma/xilinx/xilinx_dpdma.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/dma/xilinx/xilinx_dpdma.c b/drivers/dma/xilinx/xilinx_dpdma.c index d9a3542c4..bdfa85b80 100644 --- a/drivers/dma/xilinx/xilinx_dpdma.c +++ b/drivers/dma/xilinx/xilinx_dpdma.c @@ -730,6 +730,9 @@ xilinx_dpdma_chan_prep_cyclic(struct xilinx_dpdma_chan *chan, last = sw_desc; } + if (list_empty(&tx_desc->descriptors)) + goto error; + sw_desc = list_first_entry(&tx_desc->descriptors, struct xilinx_dpdma_sw_desc, node); last->hw.next_desc = lower_32_bits(sw_desc->dma_addr); -- 2.30.2