| Message ID | 20200520131558.23009-1-tomi.valkeinen@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | media: videobuf2-dma-contig: fix bad kfree in vb2_dma_contig_clear_max_seg_size | expand |
Hi Tomi, On 20.05.2020 15:15, Tomi Valkeinen wrote: > Commit 9495b7e92f716ab2bd6814fab5e97ab4a39adfdd ("driver core: platform: > Initialize dma_parms for platform devices") in v5.7-rc5 causes > vb2_dma_contig_clear_max_seg_size() to kfree memory that was not > allocated by vb2_dma_contig_set_max_seg_size(). > > The assumption in vb2_dma_contig_set_max_seg_size() seems to be that > dev->dma_parms is always NULL when the driver is probed, and the case > where dev->dma_parms has bee initialized by someone else than the driver > (by calling vb2_dma_contig_set_max_seg_size) will cause a failure. > > All the current users of these functions are platform devices, which now > always have dma_parms set by the driver core. To fix the issue for v5.7, > make vb2_dma_contig_set_max_seg_size() return an error if dma_parms is > NULL to be on the safe side, and remove the kfree code from > vb2_dma_contig_clear_max_seg_size(). > > For v5.8 we should remove the two functions and move the > dma_set_max_seg_size() calls into the drivers. > > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com> > --- > > Note: I have only fully tested this on linux-next, as the capture driver > I use doesn't support unloading modules in v5.7. > > drivers/media/common/videobuf2/videobuf2-dma-contig.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > > diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c > index d3a3ee5b597b..24f80b62ef94 100644 > --- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c > +++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c > @@ -726,9 +726,8 @@ EXPORT_SYMBOL_GPL(vb2_dma_contig_memops); > int vb2_dma_contig_set_max_seg_size(struct device *dev, unsigned int size) > { > if (!dev->dma_parms) { > - dev->dma_parms = kzalloc(sizeof(*dev->dma_parms), GFP_KERNEL); > - if (!dev->dma_parms) > - return -ENOMEM; > + dev_err(dev, "Failed to set max_seg_size: dma_parms is NULL\n"); > + return -ENODEV; > } > if (dma_get_max_seg_size(dev) < size) > return dma_set_max_seg_size(dev, size); > @@ -747,8 +746,6 @@ EXPORT_SYMBOL_GPL(vb2_dma_contig_set_max_seg_size); > */ > void vb2_dma_contig_clear_max_seg_size(struct device *dev) > { > - kfree(dev->dma_parms); > - dev->dma_parms = NULL; > } > EXPORT_SYMBOL_GPL(vb2_dma_contig_clear_max_seg_size); We don't need to export empty function imho. It can be made an empty static inline in include/media/videobuf2-dma-contig.h. Best regards
On Wed, 20 May 2020 at 15:16, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote: > > Commit 9495b7e92f716ab2bd6814fab5e97ab4a39adfdd ("driver core: platform: > Initialize dma_parms for platform devices") in v5.7-rc5 causes > vb2_dma_contig_clear_max_seg_size() to kfree memory that was not > allocated by vb2_dma_contig_set_max_seg_size(). > > The assumption in vb2_dma_contig_set_max_seg_size() seems to be that > dev->dma_parms is always NULL when the driver is probed, and the case > where dev->dma_parms has bee initialized by someone else than the driver > (by calling vb2_dma_contig_set_max_seg_size) will cause a failure. > > All the current users of these functions are platform devices, which now > always have dma_parms set by the driver core. To fix the issue for v5.7, > make vb2_dma_contig_set_max_seg_size() return an error if dma_parms is > NULL to be on the safe side, and remove the kfree code from > vb2_dma_contig_clear_max_seg_size(). Not entirely true I believe, see more below. > > For v5.8 we should remove the two functions and move the > dma_set_max_seg_size() calls into the drivers. > > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com> > --- > > Note: I have only fully tested this on linux-next, as the capture driver > I use doesn't support unloading modules in v5.7. > > drivers/media/common/videobuf2/videobuf2-dma-contig.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > > diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c > index d3a3ee5b597b..24f80b62ef94 100644 > --- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c > +++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c > @@ -726,9 +726,8 @@ EXPORT_SYMBOL_GPL(vb2_dma_contig_memops); > int vb2_dma_contig_set_max_seg_size(struct device *dev, unsigned int size) > { > if (!dev->dma_parms) { > - dev->dma_parms = kzalloc(sizeof(*dev->dma_parms), GFP_KERNEL); > - if (!dev->dma_parms) > - return -ENOMEM; > + dev_err(dev, "Failed to set max_seg_size: dma_parms is NULL\n"); > + return -ENODEV; > } > if (dma_get_max_seg_size(dev) < size) > return dma_set_max_seg_size(dev, size); > @@ -747,8 +746,6 @@ EXPORT_SYMBOL_GPL(vb2_dma_contig_set_max_seg_size); > */ > void vb2_dma_contig_clear_max_seg_size(struct device *dev) > { > - kfree(dev->dma_parms); > - dev->dma_parms = NULL; > } > EXPORT_SYMBOL_GPL(vb2_dma_contig_clear_max_seg_size); I think you need something along the lines of this as well: diff --git a/drivers/media/platform/s5p-mfc/s5p_mfc.c b/drivers/media/platform/s5p-mfc/s5p_mfc.c index 5c2a23b953a4..7acf2a03812d 100644 --- a/drivers/media/platform/s5p-mfc/s5p_mfc.c +++ b/drivers/media/platform/s5p-mfc/s5p_mfc.c @@ -1070,6 +1070,7 @@ static const struct v4l2_file_operations s5p_mfc_fops = { /* DMA memory related helper functions */ static void s5p_mfc_memdev_release(struct device *dev) { + kfree(dev->dma_parms); of_reserved_mem_device_release(dev); } @@ -1090,6 +1091,10 @@ static struct device *s5p_mfc_alloc_memdev(struct device *dev, child->dma_mask = dev->dma_mask; child->release = s5p_mfc_memdev_release; + child->dma_parms = kzalloc(sizeof(*child->dma_parms), GFP_KERNEL); + if (!child->dma_parms) + goto err; + /* * The memdevs are not proper OF platform devices, so in order for them * to be treated as valid DMA masters we need a bit of a hack to force @@ -1105,6 +1110,7 @@ static struct device *s5p_mfc_alloc_memdev(struct device *dev, device_del(child); } +err: put_device(child); return NULL; } Also, please tag the patch for stable. Kind regards Uffe
diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c index d3a3ee5b597b..24f80b62ef94 100644 --- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c +++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c @@ -726,9 +726,8 @@ EXPORT_SYMBOL_GPL(vb2_dma_contig_memops); int vb2_dma_contig_set_max_seg_size(struct device *dev, unsigned int size) { if (!dev->dma_parms) { - dev->dma_parms = kzalloc(sizeof(*dev->dma_parms), GFP_KERNEL); - if (!dev->dma_parms) - return -ENOMEM; + dev_err(dev, "Failed to set max_seg_size: dma_parms is NULL\n"); + return -ENODEV; } if (dma_get_max_seg_size(dev) < size) return dma_set_max_seg_size(dev, size); @@ -747,8 +746,6 @@ EXPORT_SYMBOL_GPL(vb2_dma_contig_set_max_seg_size); */ void vb2_dma_contig_clear_max_seg_size(struct device *dev) { - kfree(dev->dma_parms); - dev->dma_parms = NULL; } EXPORT_SYMBOL_GPL(vb2_dma_contig_clear_max_seg_size);
Commit 9495b7e92f716ab2bd6814fab5e97ab4a39adfdd ("driver core: platform: Initialize dma_parms for platform devices") in v5.7-rc5 causes vb2_dma_contig_clear_max_seg_size() to kfree memory that was not allocated by vb2_dma_contig_set_max_seg_size(). The assumption in vb2_dma_contig_set_max_seg_size() seems to be that dev->dma_parms is always NULL when the driver is probed, and the case where dev->dma_parms has bee initialized by someone else than the driver (by calling vb2_dma_contig_set_max_seg_size) will cause a failure. All the current users of these functions are platform devices, which now always have dma_parms set by the driver core. To fix the issue for v5.7, make vb2_dma_contig_set_max_seg_size() return an error if dma_parms is NULL to be on the safe side, and remove the kfree code from vb2_dma_contig_clear_max_seg_size(). For v5.8 we should remove the two functions and move the dma_set_max_seg_size() calls into the drivers. Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com> --- Note: I have only fully tested this on linux-next, as the capture driver I use doesn't support unloading modules in v5.7. drivers/media/common/videobuf2/videobuf2-dma-contig.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-)