On Thu, Nov 14, 2024 at 11:41:25AM +0300, Dan Carpenter wrote:
> On Thu, Nov 14, 2024 at 04:27:52PM +0800, Su Hui wrote:
> > Clang static checker(scan-build) warning：
> > drivers/bus/fsl-mc/fsl-mc-bus.c: line 909, column 2
> > Attempt to free released memory.
> >
> > When 'obj_desc->type' == "dprc" and begin to free 'mc_bus' and 'mc_dev',
> > there is a double free problem because of 'mc_dev = &mc_bus->mc_dev'.
> > Add a judgment to fix this problem.
> >
> > Fixes: a042fbed0290 ("staging: fsl-mc: simplify couple of deallocations")
> > Signed-off-by: Su Hui <suhui@xxxxxxxxxxxx>
> > ---
> > drivers/bus/fsl-mc/fsl-mc-bus.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/bus/fsl-mc/fsl-mc-bus.c b/drivers/bus/fsl-mc/fsl-mc-bus.c
> > index 930d8a3ba722..8d2d5d3cc782 100644
> > --- a/drivers/bus/fsl-mc/fsl-mc-bus.c
> > +++ b/drivers/bus/fsl-mc/fsl-mc-bus.c
> > @@ -905,8 +905,10 @@ int fsl_mc_device_add(struct fsl_mc_obj_desc *obj_desc,
> >
> > error_cleanup_dev:
> > kfree(mc_dev->regions);
> > - kfree(mc_bus);
> > - kfree(mc_dev);
> > + if (strcmp(mc_dev->obj_desc.type, "dprc") == 0)
>
> This works, but it would probably be nicer to write this as:
>
> if (is_fsl_mc_bus_dprc(mc_dev))
> kfree(mc_bus);
> else
> kfree(mc_dev);
>
> That way it would match the release function.
820 mc_dev->dev.release = fsl_mc_device_release;
[ snip ]
891 * The device-specific probe callback will get invoked by device_add()
892 */
893 error = device_add(&mc_dev->dev);
894 if (error < 0) {
895 dev_err(parent_dev,
896 "device_add() failed for device %s: %d\n",
897 dev_name(&mc_dev->dev), error);
898 goto error_cleanup_dev;
I don't think this goto is correct. I think fsl_mc_device_release() will be
called automaticall on this path so the goto is a double free.
899 }
900
901 dev_dbg(parent_dev, "added %s\n", dev_name(&mc_dev->dev));
902
903 *new_mc_dev = mc_dev;
904 return 0;
905
906 error_cleanup_dev:
907 kfree(mc_dev->regions);
908 if (is_fsl_mc_bus_dprc(mc_dev))
909 kfree(mc_bus);
910 else
911 kfree(mc_dev);
912
913 return error;
914 }
regards,
dan carpenter
