Re: [PATCH v2 3/4] dmaengine: dma-axi-dmac: fix use-after-free on unbind

[Dan Carpenter <error27@gmail.com>]

On Mon, Mar 30, 2026 at 03:32:25PM +0100, Nuno Sá wrote:
> On Mon, Mar 30, 2026 at 07:40:55AM +0800, kernel test robot wrote:
> > BCC: lkp@intel.com
> > CC: oe-kbuild-all@lists.linux.dev
> > In-Reply-To: <20260327-dma-dmac-handle-vunmap-v2-3-021f95f0e87b@analog.com>
> > References: <20260327-dma-dmac-handle-vunmap-v2-3-021f95f0e87b@analog.com>
> > TO: "Nuno Sá via B4 Relay" <devnull+nuno.sa.analog.com@kernel.org>
> > TO: dmaengine@vger.kernel.org
> > TO: linux-kernel@vger.kernel.org
> > CC: "Lars-Peter Clausen" <lars@metafoo.de>
> > CC: Vinod Koul <vkoul@kernel.org>
> > CC: Frank Li <Frank.Li@kernel.org>
> > 
> > Hi Nuno,
> > 
> > kernel test robot noticed the following build warnings:
> > 
> > [auto build test WARNING on b7560798466a07d9c3fb011698e92c335ab28baf]
> > 
> > url:    https://github.com/intel-lab-lkp/linux/commits/Nuno-S-via-B4-Relay/dmaengine-Fix-possuible-use-after-free/20260329-160000
> > base:   b7560798466a07d9c3fb011698e92c335ab28baf
> > patch link:    https://lore.kernel.org/r/20260327-dma-dmac-handle-vunmap-v2-3-021f95f0e87b%40analog.com
> > patch subject: [PATCH v2 3/4] dmaengine: dma-axi-dmac: fix use-after-free on unbind
> > :::::: branch date: 16 hours ago
> > :::::: commit date: 16 hours ago
> > config: loongarch-randconfig-r071-20260329 (https://download.01.org/0day-ci/archive/20260330/202603300705.jhDfInJk-lkp@intel.com/config)
> > compiler: loongarch64-linux-gcc (GCC) 15.2.0
> > smatch: v0.5.0-9004-gb810ac53
> > 
> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > the same patch/commit), kindly add following tags
> > | Reported-by: kernel test robot <lkp@intel.com>
> > | Reported-by: Dan Carpenter <error27@gmail.com>
> > | Closes: https://lore.kernel.org/r/202603300705.jhDfInJk-lkp@intel.com/
> > 
> > smatch warnings:
> > drivers/dma/dma-axi-dmac.c:1342 axi_dmac_probe() warn: address of NULL pointer 'dmac'
> 
> Am I missing something or is this a false positive?
> 

It is a false positive, yes.  You're using lei to see unfiltered
results.  Normally I review the warnings and hit resend on the
warnings which might be real.

regards,
dan carpenter