Hi Julia, On 29/09/2017 14:15, Julia Lawall wrote: > I'm not sure that it is allowed to do krealloc on devm allocated data. > See lins 468 and 485. >
Indeed, from a glance at the code, it does not look like it is a good idea. For v3, this piece of code will be deleted anyway so it won't be a problem anymore. However, this logic is used in drivers/pinctrl/sunxi/pinctrl-sunxi.c[1][2] @Maxime, @Chen-Yu: We should check more thoroughly than what I did but I think Julia is right. The following is my understanding from a very quick look at the code. devm_kzalloc will register gpio->functions as a res of the device. However it's possible that the pointer is different after krealloc. In that case, krealloc will free the "old" gpio->functions[3] which is managed by devres. 1) We might be exposed to a free of a NULL pointer when devres takes care of unregistering the device. 2) The "new" gpio->functions would never be freed. Is that correct? If so, we should get rid of devm_kzalloc in favor of a simple kzalloc and free the pointer in the remove function of the driver. [1] http://elixir.free-electrons.com/linux/latest/source/drivers/pinctrl/sunxi/pinctrl-sunxi.c#L1078 [2] http://elixir.free-electrons.com/linux/latest/source/drivers/pinctrl/sunxi/pinctrl-sunxi.c#L1107 [3] http://elixir.free-electrons.com/linux/latest/source/mm/slab_common.c#L1414 Thanks, Quentin > julia > > ---------- Forwarded message ---------- > Date: Fri, 29 Sep 2017 20:00:03 +0800 > From: kbuild test robot <fengguang...@intel.com> > To: kbu...@01.org > Cc: Julia Lawall <julia.law...@lip6.fr> > Subject: Re: [PATCH v2 02/10] pinctrl: axp209: add pinctrl features > > Hi Quentin, > > [auto build test WARNING on ] > > url: > https://github.com/0day-ci/linux/commits/Quentin-Schulz/add-pinmuxing-support-for-pins-in-AXP209-and-AXP813-PMICs/20170929-162846 > base: > :::::: branch date: 4 hours ago > :::::: commit date: 4 hours ago > >>> drivers/pinctrl/pinctrl-axp209.c:485:19-27: WARNING: invalid free of devm_ >>> allocated data > > # > https://github.com/0day-ci/linux/commit/1e016076fb841f90f047d2b001c9f8d9fd5e2953 > git remote add linux-review https://github.com/0day-ci/linux > git remote update linux-review > git checkout 1e016076fb841f90f047d2b001c9f8d9fd5e2953 > vim +485 drivers/pinctrl/pinctrl-axp209.c > > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 446 > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 447 > static int axp20x_build_state(struct platform_device *pdev) > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 448 { > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 449 > struct axp20x_gpio *gpio = platform_get_drvdata(pdev); > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 450 > unsigned int npins = gpio->desc->npins; > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 451 > const struct axp20x_desc_pin *pin; > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 452 > struct axp20x_desc_function *func; > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 453 > int i, ret; > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 454 > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 455 > gpio->ngroups = npins; > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 456 > gpio->groups = devm_kzalloc(&pdev->dev, > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 457 > gpio->ngroups * sizeof(*gpio->groups), > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 458 > GFP_KERNEL); > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 459 > if (!gpio->groups) > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 460 > return -ENOMEM; > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 461 > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 462 > for (i = 0; i < npins; i++) { > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 463 > gpio->groups[i].name = gpio->desc->pins[i].pin.name; > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 464 > gpio->groups[i].pin = gpio->desc->pins[i].pin.number; > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 465 > } > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 466 > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 467 > /* We assume 4 functions per pin should be enough as a default max */ > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 468 > gpio->functions = devm_kzalloc(&pdev->dev, > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 469 > npins * 4 * sizeof(*gpio->functions), > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 470 > GFP_KERNEL); > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 471 > if (!gpio->functions) > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 472 > return -ENOMEM; > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 473 > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 474 > /* Create a list of uniquely named functions */ > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 475 > for (i = 0; i < npins; i++) { > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 476 > pin = &gpio->desc->pins[i]; > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 477 > func = pin->functions; > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 478 > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 479 > while (func->name) { > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 480 > axp20x_pinctrl_add_function(gpio, func->name); > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 481 > func++; > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 482 > } > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 483 > } > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 484 > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 @485 > gpio->functions = krealloc(gpio->functions, > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 486 > gpio->nfunctions * sizeof(*gpio->functions), > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 487 > GFP_KERNEL); > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 488 > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 489 > for (i = 0; i < npins; i++) { > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 490 > pin = &gpio->desc->pins[i]; > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 491 > ret = axp20x_attach_group_function(pdev, pin); > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 492 > if (ret) > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 493 > return ret; > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 494 > } > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 495 > 1e016076fb drivers/pinctrl/pinctrl-axp209.c Quentin Schulz 2017-09-26 496 > return 0; > f72f4b44df drivers/gpio/gpio-axp209.c Maxime Ripard 2016-07-20 497 } > f72f4b44df drivers/gpio/gpio-axp209.c Maxime Ripard 2016-07-20 498 > > --- > 0-DAY kernel test infrastructure Open Source Technology Center > https://lists.01.org/pipermail/kbuild-all Intel Corporation > -- Quentin Schulz, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
