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[31.209.40.223]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6a38c9d5eb2sm841941a12.5.2026.08.14.06.29.42 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Fri, 14 Aug 2026 06:29:44 -0700 (PDT) From: Christian Lugnberg To: vkoul@kernel.org Cc: Frank.Li@kernel.org, wens@kernel.org, jernej.skrabec@gmail.com, samuel@sholland.org, dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev, linux-kernel@vger.kernel.org, Christian Lugnberg , stable@vger.kernel.org Subject: [PATCH 2/2] dmaengine: sun6i: fix null pointer dereference in sun6i_dma_tx_status Date: Fri, 14 Aug 2026 15:28:30 +0200 Message-ID: <20260814132906.70322-3-christian.lugnberg@soundtrack.io> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260814132906.70322-1-christian.lugnberg@soundtrack.io> References: <20260814132906.70322-1-christian.lugnberg@soundtrack.io> Precedence: bulk X-Mailing-List: linux-sunxi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Rspamd-Server: rspamd-worker-8404 X-Spamd-Result: default: False [0.84 / 15.00]; BAYES_HAM(-5.50)[100.00%]; RBL_SENDERSCORE(2.00)[172.232.135.74:from]; DMARC_POLICY_QUARANTINE(1.50)[soundtrack.io : SPF not aligned (relaxed), No valid DKIM,quarantine]; SUSPICIOUS_RECIPS(1.50)[]; MID_CONTAINS_FROM(1.00)[]; R_MISSING_CHARSET(0.50)[]; MAILLIST(-0.15)[generic]; BAD_REP_POLICIES(0.10)[]; MIME_GOOD(-0.10)[text/plain]; HAS_LIST_UNSUB(-0.01)[]; PRECEDENCE_BULK(0.00)[]; TAGGED_RCPT(0.00)[]; FREEMAIL_CC(0.00)[kernel.org,gmail.com,sholland.org,vger.kernel.org,lists.infradead.org,lists.linux.dev,soundtrack.io]; ARC_ALLOW(0.00)[subspace.kernel.org:s=arc-20240116:i=1]; FROM_HAS_DN(0.00)[]; RCVD_COUNT_FIVE(0.00)[6]; ASN(0.00)[asn:63949, ipnet:172.232.128.0/19, country:SG]; RCPT_COUNT_SEVEN(0.00)[11]; R_SPF_ALLOW(0.00)[+ip4:172.232.135.74]; TO_DN_SOME(0.00)[]; FORGED_SENDER_MAILLIST(0.00)[]; FORGED_RECIPIENTS_MAILLIST(0.00)[]; RCVD_TLS_LAST(0.00)[]; MIME_TRACE(0.00)[0:+]; TAGGED_FROM(0.00)[bounces-25160-noreply=patchwork.local]; FROM_NEQ_ENVFROM(0.00)[christian.lugnberg@soundtrack.io,linux-sunxi@lists.linux.dev]; RCVD_VIA_SMTP_AUTH(0.00)[] X-Rspamd-Queue-Id: 786E81C055D X-MORS-Enabled: yes X-MORS-DOMAIN: patchwork.local X-MORS-HOSTING: hosting172546 X-MORS-USER: hosting172546 X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= sun6i_dma_tx_status() calls vchan_find_desc() to look up the virtual descriptor for a given cookie, then unconditionally dereferences the result via to_sun6i_desc() before checking whether the pointer is NULL: vd = vchan_find_desc(&vchan->vc, cookie); txd = to_sun6i_desc(&vd->tx); /* vd may be NULL here */ if (vd) { for (lli = txd->v_lli; ...) vchan_find_desc() returns NULL when the descriptor has already been completed or is in-flight on a physical channel and no longer present in the virtual channel's descriptor list. Dereferencing NULL via to_sun6i_desc() in that case is undefined behaviour and will oops on any architecture that faults on NULL pointer access. Move the to_sun6i_desc() call inside the if (vd) block so it is only reached when vd is known to be non-NULL: vd = vchan_find_desc(&vchan->vc, cookie); if (vd) { struct sun6i_desc *txd = to_sun6i_desc(&vd->tx); for (lli = txd->v_lli; ...) Fixes: 555859308723 ("dmaengine: sun6i: Add driver for the Allwinner A31 DMA controller") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-sonnet-4-6 Signed-off-by: Christian Lugnberg --- drivers/dma/sun6i-dma.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c index 04fe1f5042e9..7704b016aed8 100644 --- a/drivers/dma/sun6i-dma.c +++ b/drivers/dma/sun6i-dma.c @@ -981,7 +981,6 @@ static enum dma_status sun6i_dma_tx_status(struct dma_chan *chan, struct sun6i_pchan *pchan = vchan->phy; struct sun6i_dma_lli *lli; struct virt_dma_desc *vd; - struct sun6i_desc *txd; enum dma_status ret; unsigned long flags; size_t bytes = 0; @@ -993,9 +992,9 @@ static enum dma_status sun6i_dma_tx_status(struct dma_chan *chan, spin_lock_irqsave(&vchan->vc.lock, flags); vd = vchan_find_desc(&vchan->vc, cookie); - txd = to_sun6i_desc(&vd->tx); if (vd) { + struct sun6i_desc *txd = to_sun6i_desc(&vd->tx); for (lli = txd->v_lli; lli != NULL; lli = lli->v_lli_next) bytes += lli->len; } else if (!pchan || !pchan->desc) {