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Sat, 13 Jun 2026 00:46:23 -0700 (PDT) From: Jernej =?UTF-8?B?xaBrcmFiZWM=?= To: vkoul@kernel.org, Frank.Li@kernel.org, wens@kernel.org, samuel@sholland.org, mripard@kernel.org, arnd@arndb.de, Hongling Zeng Cc: dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev, linux-kernel@vger.kernel.org, zhongling0719@126.com, Hongling Zeng Subject: Re: [PATCH] dmaengine: sun6i-dma: Fix use-after-free in error handling paths Date: Sat, 13 Jun 2026 09:46:19 +0200 Message-ID: In-Reply-To: <20260611063631.96566-1-zenghongling@kylinos.cn> References: <20260611063631.96566-1-zenghongling@kylinos.cn> 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" Dne =C4=8Detrtek, 11. junij 2026 ob 08:36:31 Srednjeevropski poletni =C4=8D= as je Hongling Zeng napisal(a): > In error handling paths, the for loop frees v_lli in the loop body, > then accesses v_lli->v_lli_next and v_lli->p_lli_next in the > increment expression, which is use-after-free. >=20 > Fix by saving both the next virtual and physical pointers before > freeing the current node. >=20 > Fixes: 555859308723 ("dmaengine: Add driver for Allwinner sun6i DMA") > Signed-off-by: Hongling Zeng > --- > drivers/dma/sun6i-dma.c | 20 ++++++++++++++++---- > 1 file changed, 16 insertions(+), 4 deletions(-) >=20 > diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c > index a9a254dbf8cb..eb9c4ae87ac8 100644 > --- a/drivers/dma/sun6i-dma.c > +++ b/drivers/dma/sun6i-dma.c > @@ -788,9 +788,15 @@ static struct dma_async_tx_descriptor *sun6i_dma_pre= p_slave_sg( > return vchan_tx_prep(&vchan->vc, &txd->vd, flags); > =20 > err_lli_free: > - for (p_lli =3D txd->p_lli, v_lli =3D txd->v_lli; v_lli; > - p_lli =3D v_lli->p_lli_next, v_lli =3D v_lli->v_lli_next) > + p_lli =3D txd->p_lli; > + v_lli =3D txd->v_lli; > + while (v_lli) { > + struct sun6i_dma_lli *next_v_lli =3D v_lli->v_lli_next; > + dma_addr_t next_p_lli =3D v_lli->p_lli_next; > dma_pool_free(sdev->pool, v_lli, p_lli); > + v_lli =3D next_v_lli; > + p_lli =3D next_p_lli; > + } > kfree(txd); > return NULL; > } > @@ -869,9 +875,15 @@ static struct dma_async_tx_descriptor *sun6i_dma_pre= p_dma_cyclic( > return vchan_tx_prep(&vchan->vc, &txd->vd, flags); > =20 > err_lli_free: > - for (p_lli =3D txd->p_lli, v_lli =3D txd->v_lli; v_lli; > - p_lli =3D v_lli->p_lli_next, v_lli =3D v_lli->v_lli_next) > + p_lli =3D txd->p_lli; > + v_lli =3D txd->v_lli; > + while (v_lli) { > + struct sun6i_dma_lli *next_v_lli =3D v_lli->v_lli_next; > + dma_addr_t next_p_lli =3D v_lli->p_lli_next; > dma_pool_free(sdev->pool, v_lli, p_lli); > + v_lli =3D next_v_lli; > + p_lli =3D next_p_lli; > + } > kfree(txd); > return NULL; > } >=20 This is certainly a valid fix, but it's replicating what sun6i_dma_free_des= c() is already doing. It would be better to split code to accept struct sun6i_d= esc *txd parameter and call that instead from all places. Best regards, Jernej