* [PATCH] staging: comedi: drivers: Fix memory leak in gsc_hpdi_auto_attach @ 2019-12-15 1:33 Navid Emamdoost 2019-12-15 15:07 ` Markus Elfring 2019-12-16 10:36 ` Ian Abbott 0 siblings, 2 replies; 4+ messages in thread From: Navid Emamdoost @ 2019-12-15 1:33 UTC (permalink / raw) To: Ian Abbott, H Hartley Sweeten, Greg Kroah-Hartman, Navid Emamdoost, devel, linux-kernel Cc: emamd001 In the implementation of gsc_hpdi_auto_attach(), the allocated dma description is leaks in case of alignment error, or failure of gsc_hpdi_setup_dma_descriptors() or comedi_alloc_subdevices(). Release devpriv->dma_desc via dma_free_coherent(). Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com> --- drivers/staging/comedi/drivers/gsc_hpdi.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/drivers/staging/comedi/drivers/gsc_hpdi.c b/drivers/staging/comedi/drivers/gsc_hpdi.c index 4bdf44d82879..c0c7047a6d1b 100644 --- a/drivers/staging/comedi/drivers/gsc_hpdi.c +++ b/drivers/staging/comedi/drivers/gsc_hpdi.c @@ -633,16 +633,17 @@ static int gsc_hpdi_auto_attach(struct comedi_device *dev, if (devpriv->dma_desc_phys_addr & 0xf) { dev_warn(dev->class_dev, " dma descriptors not quad-word aligned (bug)\n"); - return -EIO; + retval = -EIO; + goto release_dma_desc; } retval = gsc_hpdi_setup_dma_descriptors(dev, 0x1000); if (retval < 0) - return retval; + goto release_dma_desc; retval = comedi_alloc_subdevices(dev, 1); if (retval) - return retval; + goto release_dma_desc; /* Digital I/O subdevice */ s = &dev->subdevices[0]; @@ -660,6 +661,15 @@ static int gsc_hpdi_auto_attach(struct comedi_device *dev, s->cancel = gsc_hpdi_cancel; return gsc_hpdi_init(dev); + +release_dma_desc: + if (devpriv->dma_desc) + dma_free_coherent(&pcidev->dev, + sizeof(struct plx_dma_desc) * + NUM_DMA_DESCRIPTORS, + devpriv->dma_desc, + devpriv->dma_desc_phys_addr); + return retval; } static void gsc_hpdi_detach(struct comedi_device *dev) -- 2.17.1 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] staging: comedi: drivers: Fix memory leak in gsc_hpdi_auto_attach 2019-12-15 1:33 [PATCH] staging: comedi: drivers: Fix memory leak in gsc_hpdi_auto_attach Navid Emamdoost @ 2019-12-15 15:07 ` Markus Elfring 2019-12-16 10:36 ` Ian Abbott 1 sibling, 0 replies; 4+ messages in thread From: Markus Elfring @ 2019-12-15 15:07 UTC (permalink / raw) To: Navid Emamdoost, devel Cc: linux-kernel, kernel-janitors, Greg Kroah-Hartman, H Hartley Sweeten, Ian Abbott, Navid Emamdoost > In the implementation of gsc_hpdi_auto_attach(), the allocated dma > description is leaks in case of alignment error, … Please avoid a typo in this change message. … +++ b/drivers/staging/comedi/drivers/gsc_hpdi.c … > @@ -660,6 +661,15 @@ static int gsc_hpdi_auto_attach(struct comedi_device *dev, > s->cancel = gsc_hpdi_cancel; > > return gsc_hpdi_init(dev); > + > +release_dma_desc: > + if (devpriv->dma_desc) > + dma_free_coherent(&pcidev->dev, > + sizeof(struct plx_dma_desc) * > + NUM_DMA_DESCRIPTORS, > + devpriv->dma_desc, > + devpriv->dma_desc_phys_addr); > + return retval; > } > > static void gsc_hpdi_detach(struct comedi_device *dev) I got the impression that return values from calls of the function “dma_alloc_coherent” should be checked before. * Would you like to add null pointer checks at other source code places? * Should the jump targets be accordingly adjusted then for the completion of the desired exception handling? Regards, Markus ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] staging: comedi: drivers: Fix memory leak in gsc_hpdi_auto_attach 2019-12-15 1:33 [PATCH] staging: comedi: drivers: Fix memory leak in gsc_hpdi_auto_attach Navid Emamdoost 2019-12-15 15:07 ` Markus Elfring @ 2019-12-16 10:36 ` Ian Abbott 2019-12-16 20:18 ` Navid Emamdoost 1 sibling, 1 reply; 4+ messages in thread From: Ian Abbott @ 2019-12-16 10:36 UTC (permalink / raw) To: Navid Emamdoost, H Hartley Sweeten, Greg Kroah-Hartman, devel, linux-kernel Cc: emamd001 On 15/12/2019 01:33, Navid Emamdoost wrote: > In the implementation of gsc_hpdi_auto_attach(), the allocated dma > description is leaks in case of alignment error, or failure of > gsc_hpdi_setup_dma_descriptors() or comedi_alloc_subdevices(). Release > devpriv->dma_desc via dma_free_coherent(). > > Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com> Actually, there is no memory leak (although there is another problem that I'll mention below). If the "auto_attach" handler gsc_hpdi_auto_attach() returns an error, then the "detach" handler gsc_hpdi_detach() will be called automatically to clean up. (This is true for all comedi drivers). gsc_hpdi_detach() calls gsc_hpdi_free_dma() to free the DMA buffers and DMA descriptors. > --- > drivers/staging/comedi/drivers/gsc_hpdi.c | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > diff --git a/drivers/staging/comedi/drivers/gsc_hpdi.c b/drivers/staging/comedi/drivers/gsc_hpdi.c > index 4bdf44d82879..c0c7047a6d1b 100644 > --- a/drivers/staging/comedi/drivers/gsc_hpdi.c > +++ b/drivers/staging/comedi/drivers/gsc_hpdi.c > @@ -633,16 +633,17 @@ static int gsc_hpdi_auto_attach(struct comedi_device *dev, > if (devpriv->dma_desc_phys_addr & 0xf) { > dev_warn(dev->class_dev, > " dma descriptors not quad-word aligned (bug)\n"); > - return -EIO; > + retval = -EIO; > + goto release_dma_desc; > } > > retval = gsc_hpdi_setup_dma_descriptors(dev, 0x1000); > if (retval < 0) > - return retval; > + goto release_dma_desc; > > retval = comedi_alloc_subdevices(dev, 1); > if (retval) > - return retval; > + goto release_dma_desc; > > /* Digital I/O subdevice */ > s = &dev->subdevices[0]; > @@ -660,6 +661,15 @@ static int gsc_hpdi_auto_attach(struct comedi_device *dev, > s->cancel = gsc_hpdi_cancel; > > return gsc_hpdi_init(dev); > + > +release_dma_desc: > + if (devpriv->dma_desc) > + dma_free_coherent(&pcidev->dev, > + sizeof(struct plx_dma_desc) * > + NUM_DMA_DESCRIPTORS, > + devpriv->dma_desc, > + devpriv->dma_desc_phys_addr); > + return retval; > } > > static void gsc_hpdi_detach(struct comedi_device *dev) > This patch could actually result in devpriv->dma_desc being freed twice - once in the 'release_dma_desc:' code and again when gsc_hpdi_detach() is called externally as part of the clean-up. The real bug in the original code is that it does not check whether any of the calls to dma_alloc_coherent() returned NULL. If any of the calls to dma_alloc_coherent() returns NULL, gsc_hpdi_auto_attach() needs to return an error (-ENOMEM). The subsequent call to gsc_hpdi_detach() will then free whatever DMA coherent buffers where allocated. -- -=( Ian Abbott <abbotti@mev.co.uk> || Web: www.mev.co.uk )=- -=( MEV Ltd. is a company registered in England & Wales. )=- -=( Registered number: 02862268. Registered address: )=- -=( 15 West Park Road, Bramhall, STOCKPORT, SK7 3JZ, UK. )=- ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] staging: comedi: drivers: Fix memory leak in gsc_hpdi_auto_attach 2019-12-16 10:36 ` Ian Abbott @ 2019-12-16 20:18 ` Navid Emamdoost 0 siblings, 0 replies; 4+ messages in thread From: Navid Emamdoost @ 2019-12-16 20:18 UTC (permalink / raw) To: Ian Abbott Cc: H Hartley Sweeten, Greg Kroah-Hartman, devel, LKML, Navid Emamdoost Ian, thanks for your feedback. On Mon, Dec 16, 2019 at 4:36 AM Ian Abbott <abbotti@mev.co.uk> wrote: > > On 15/12/2019 01:33, Navid Emamdoost wrote: > > In the implementation of gsc_hpdi_auto_attach(), the allocated dma > > description is leaks in case of alignment error, or failure of > > gsc_hpdi_setup_dma_descriptors() or comedi_alloc_subdevices(). Release > > devpriv->dma_desc via dma_free_coherent(). > > > > Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com> > > Actually, there is no memory leak (although there is another problem > that I'll mention below). If the "auto_attach" handler > gsc_hpdi_auto_attach() returns an error, then the "detach" handler > gsc_hpdi_detach() will be called automatically to clean up. (This is > true for all comedi drivers). gsc_hpdi_detach() calls > gsc_hpdi_free_dma() to free the DMA buffers and DMA descriptors. > I was aware that comedi_alloc_devpriv() is a resource managed allocation, but was not sure how subsequent dma_desc allocation will be handled when device detach. > > --- > > drivers/staging/comedi/drivers/gsc_hpdi.c | 16 +++++++++++++--- > > 1 file changed, 13 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/staging/comedi/drivers/gsc_hpdi.c b/drivers/staging/comedi/drivers/gsc_hpdi.c > > index 4bdf44d82879..c0c7047a6d1b 100644 > > --- a/drivers/staging/comedi/drivers/gsc_hpdi.c > > +++ b/drivers/staging/comedi/drivers/gsc_hpdi.c > > @@ -633,16 +633,17 @@ static int gsc_hpdi_auto_attach(struct comedi_device *dev, > > if (devpriv->dma_desc_phys_addr & 0xf) { > > dev_warn(dev->class_dev, > > " dma descriptors not quad-word aligned (bug)\n"); > > - return -EIO; > > + retval = -EIO; > > + goto release_dma_desc; > > } > > > > retval = gsc_hpdi_setup_dma_descriptors(dev, 0x1000); > > if (retval < 0) > > - return retval; > > + goto release_dma_desc; > > > > retval = comedi_alloc_subdevices(dev, 1); > > if (retval) > > - return retval; > > + goto release_dma_desc; > > > > /* Digital I/O subdevice */ > > s = &dev->subdevices[0]; > > @@ -660,6 +661,15 @@ static int gsc_hpdi_auto_attach(struct comedi_device *dev, > > s->cancel = gsc_hpdi_cancel; > > > > return gsc_hpdi_init(dev); > > + > > +release_dma_desc: > > + if (devpriv->dma_desc) > > + dma_free_coherent(&pcidev->dev, > > + sizeof(struct plx_dma_desc) * > > + NUM_DMA_DESCRIPTORS, > > + devpriv->dma_desc, > > + devpriv->dma_desc_phys_addr); > > + return retval; > > } > > > > static void gsc_hpdi_detach(struct comedi_device *dev) > > > > This patch could actually result in devpriv->dma_desc being freed twice > - once in the 'release_dma_desc:' code and again when gsc_hpdi_detach() > is called externally as part of the clean-up. > > The real bug in the original code is that it does not check whether any > of the calls to dma_alloc_coherent() returned NULL. If any of the calls > to dma_alloc_coherent() returns NULL, gsc_hpdi_auto_attach() needs to > return an error (-ENOMEM). The subsequent call to gsc_hpdi_detach() > will then free whatever DMA coherent buffers where allocated. > Yes, this potential null deref is another type of bug, which I will send a patch for separately. > -- > -=( Ian Abbott <abbotti@mev.co.uk> || Web: www.mev.co.uk )=- > -=( MEV Ltd. is a company registered in England & Wales. )=- > -=( Registered number: 02862268. Registered address: )=- > -=( 15 West Park Road, Bramhall, STOCKPORT, SK7 3JZ, UK. )=- -- Navid. ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-12-16 20:18 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2019-12-15 1:33 [PATCH] staging: comedi: drivers: Fix memory leak in gsc_hpdi_auto_attach Navid Emamdoost 2019-12-15 15:07 ` Markus Elfring 2019-12-16 10:36 ` Ian Abbott 2019-12-16 20:18 ` Navid Emamdoost
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