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([117.133.183.252]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-39d775c02b4sm2499630a91.14.2026.09.09.19.16.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Sep 2026 19:17:01 -0700 (PDT) From: Baineng Shou To: vkoul@kernel.org Cc: Frank.Li@kernel.org, dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, Baineng Shou Subject: [PATCH v2] dmaengine: mmp_pdma: fix wrong sg length in mmp_pdma_prep_slave_sg() Date: Thu, 10 Sep 2026 10:16:52 +0800 Message-Id: <20260910021652.1296640-1-shoubaineng@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In mmp_pdma_prep_slave_sg(), for_each_sg() iterates the scatterlist putting each entry into 'sg', but the entry length is read from 'sgl' (the list head) instead of 'sg' (the current entry): for_each_sg(sgl, sg, sg_len, i) { addr = sg_dma_address(sg); avail = sg_dma_len(sgl); /* should be 'sg' */ Consequently 'avail' is always the length of the first entry. For multi-sg lists this causes out-of-bounds reads when a later entry is shorter than the first, and silent data loss when it is longer. Single-sg or uniformly-sized lists happen to mask the issue. Fixes: c8acd6aa6bed3 ("dmaengine: mmp-pdma support") Signed-off-by: Baineng Shou --- Changes in v2: - Add () to the function name in the subject, per Frank Li's review. drivers/dma/mmp_pdma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c index 386e85cd4882..e90fd2023af7 100644 --- a/drivers/dma/mmp_pdma.c +++ b/drivers/dma/mmp_pdma.c @@ -713,7 +713,7 @@ mmp_pdma_prep_slave_sg(struct dma_chan *dchan, struct scatterlist *sgl, for_each_sg(sgl, sg, sg_len, i) { addr = sg_dma_address(sg); - avail = sg_dma_len(sgl); + avail = sg_dma_len(sg); do { len = min_t(size_t, avail, PDMA_MAX_DESC_BYTES); -- 2.34.1