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Mon, 05 Jan 2026 18:59:32 -0800 (PST) Date: Mon, 5 Jan 2026 21:59:29 -0500 From: Samuel Kayode To: Waqar Hameed Cc: Sebastian Reichel , Frank Li , Lee Jones , kernel@axis.com, imx@lists.linux.dev, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 07/11] power: supply: pf1550: Fix use-after-free in power_supply_changed() Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Sat, Dec 20, 2025 at 11:36:01PM +0100, Waqar Hameed wrote: > Using the `devm_` variant for requesting IRQ _before_ the `devm_` > variant for allocating/registering the `power_supply` handle, means that > the `power_supply` handle will be deallocated/unregistered _before_ the > interrupt handler (since `devm_` naturally deallocates in reverse > allocation order). This means that during removal, there is a race > condition where an interrupt can fire just _after_ the `power_supply` > handle has been freed, *but* just _before_ the corresponding > unregistration of the IRQ handler has run. > > This will lead to the IRQ handler calling `power_supply_changed()` with > a freed `power_supply` handle. Which usually crashes the system or > otherwise silently corrupts the memory... > > Note that there is a similar situation which can also happen during > `probe()`; the possibility of an interrupt firing _before_ registering > the `power_supply` handle. This would then lead to the nasty situation > of using the `power_supply` handle *uninitialized* in > `power_supply_changed()`. > > Fix this racy use-after-free by making sure the IRQ is requested _after_ > the registration of the `power_supply` handle. > > Fixes: 4b6b6433a97d ("power: supply: pf1550: add battery charger support") > Signed-off-by: Waqar Hameed Reviewed-by: Samuel Kayode Thank you! Sam > --- > drivers/power/supply/pf1550-charger.c | 32 +++++++++++++-------------- > 1 file changed, 16 insertions(+), 16 deletions(-) > > diff --git a/drivers/power/supply/pf1550-charger.c b/drivers/power/supply/pf1550-charger.c > index 98f1ee8eca3bc..a457862ef4610 100644 > --- a/drivers/power/supply/pf1550-charger.c > +++ b/drivers/power/supply/pf1550-charger.c > @@ -584,22 +584,6 @@ static int pf1550_charger_probe(struct platform_device *pdev) > return dev_err_probe(chg->dev, ret, > "failed to add battery sense work\n"); > > - for (i = 0; i < PF1550_CHARGER_IRQ_NR; i++) { > - irq = platform_get_irq(pdev, i); > - if (irq < 0) > - return irq; > - > - chg->virqs[i] = irq; > - > - ret = devm_request_threaded_irq(&pdev->dev, irq, NULL, > - pf1550_charger_irq_handler, > - IRQF_NO_SUSPEND, > - "pf1550-charger", chg); > - if (ret) > - return dev_err_probe(&pdev->dev, ret, > - "failed irq request\n"); > - } > - > psy_cfg.drv_data = chg; > > chg->charger = devm_power_supply_register(&pdev->dev, > @@ -616,6 +600,22 @@ static int pf1550_charger_probe(struct platform_device *pdev) > return dev_err_probe(&pdev->dev, PTR_ERR(chg->battery), > "failed: power supply register\n"); > > + for (i = 0; i < PF1550_CHARGER_IRQ_NR; i++) { > + irq = platform_get_irq(pdev, i); > + if (irq < 0) > + return irq; > + > + chg->virqs[i] = irq; > + > + ret = devm_request_threaded_irq(&pdev->dev, irq, NULL, > + pf1550_charger_irq_handler, > + IRQF_NO_SUSPEND, > + "pf1550-charger", chg); > + if (ret) > + return dev_err_probe(&pdev->dev, ret, > + "failed irq request\n"); > + } > + > pf1550_dt_parse_dev_info(chg); > > return pf1550_reg_init(chg);