| Message ID | 20240328091021.18027-1-amishin@t-argos.ru |
|---|---|
| State | New |
| Headers | show |
| Series | gpio: davinci: Fix potential buffer overflow | expand |
On Thu, Mar 28, 2024 at 12:10:21PM +0300, Aleksandr Mishin wrote: > In davinci_gpio_probe() accessing an element of array 'chips->regs' of size 5 and > array 'offset_array' of size 5 can lead to a buffer overflow, since the index > 'bank' can have an out of range value 63. ^^ Where does this 63 come from? SVACE is a static analysis tool. I would have thought a static checker would say that 'bank' goes up to UINT_MAX / 32. This stuff comes from device tree though, so it looks fine to me. Documentation/devicetree/bindings/gpio/gpio-davinci.yaml: ti,ngpio = <144>; Documentation/devicetree/bindings/gpio/gpio-davinci.yaml: ti,ngpio = <32>; Documentation/devicetree/bindings/gpio/gpio-davinci.yaml: ti,ngpio = <56>; arch/arm/boot/dts/ti/davinci/da850.dtsi: ti,ngpio = <144>; So it's fine. I'm not the maintainer of this file so I don't know if adding a sanity check makes sense but if we wanted to do that we'd have to add it to davinci_gpio_get_pdata(). Otherwise it would have already had a buffer overflow earlier in the probe function when we do: drivers/gpio/gpio-davinci.c 223 if (pdata->gpio_unbanked) 224 nirq = pdata->gpio_unbanked; 225 else 226 nirq = DIV_ROUND_UP(ngpio, 16); 227 228 chips = devm_kzalloc(dev, sizeof(*chips), GFP_KERNEL); 229 if (!chips) 230 return -ENOMEM; 231 232 gpio_base = devm_platform_ioremap_resource(pdev, 0); 233 if (IS_ERR(gpio_base)) 234 return PTR_ERR(gpio_base); 235 236 for (i = 0; i < nirq; i++) { 237 chips->irqs[i] = platform_get_irq(pdev, i); ^^^ 238 if (chips->irqs[i] < 0) 239 return chips->irqs[i]; 240 } regards, dan carpenter
From: Aleksandr Mishin <amishin@t-argos.ru> Date: Thu, 28 Mar 2024 12:10:21 +0300 > In davinci_gpio_probe() accessing an element of array 'chips->regs' of size 5 and > array 'offset_array' of size 5 can lead to a buffer overflow, since the index > 'bank' can have an out of range value 63. > Fix this bug by limiting top index value. > > Found by Linux Verification Center (linuxtesting.org) with SVACE. > > Fixes: c809e37a3b5a ("gpio: davinci: Allocate the correct amount of memory for controller") > Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru> > --- > drivers/gpio/gpio-davinci.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpio/gpio-davinci.c b/drivers/gpio/gpio-davinci.c > index bb499e362912..b65df1f2b83f 100644 > --- a/drivers/gpio/gpio-davinci.c > +++ b/drivers/gpio/gpio-davinci.c > @@ -257,6 +257,9 @@ static int davinci_gpio_probe(struct platform_device *pdev) > spin_lock_init(&chips->lock); > > nbank = DIV_ROUND_UP(ngpio, 32); > + if (nbank > MAX_REGS_BANKS || nbank > 5) { > + nbank = MAX_REGS_BANKS < 5 ? MAX_REGS_BANKS : 5; > + } Static analysis warnings make no sense until you provide a reliable way to trigger the problem on real systems. > for (bank = 0; bank < nbank; bank++) > chips->regs[bank] = gpio_base + offset_array[bank]; > Thanks, Olek
28.03.2024 18:27, Alexander Lobakin пишет: > From: Aleksandr Mishin <amishin@t-argos.ru> > Date: Thu, 28 Mar 2024 12:10:21 +0300 > >> In davinci_gpio_probe() accessing an element of array 'chips->regs' of size 5 and >> array 'offset_array' of size 5 can lead to a buffer overflow, since the index >> 'bank' can have an out of range value 63. >> Fix this bug by limiting top index value. >> >> Found by Linux Verification Center (linuxtesting.org) with SVACE. >> >> Fixes: c809e37a3b5a ("gpio: davinci: Allocate the correct amount of memory for controller") >> Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru> >> --- >> drivers/gpio/gpio-davinci.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/drivers/gpio/gpio-davinci.c b/drivers/gpio/gpio-davinci.c >> index bb499e362912..b65df1f2b83f 100644 >> --- a/drivers/gpio/gpio-davinci.c >> +++ b/drivers/gpio/gpio-davinci.c >> @@ -257,6 +257,9 @@ static int davinci_gpio_probe(struct platform_device *pdev) >> spin_lock_init(&chips->lock); >> >> nbank = DIV_ROUND_UP(ngpio, 32); >> + if (nbank > MAX_REGS_BANKS || nbank > 5) { >> + nbank = MAX_REGS_BANKS < 5 ? MAX_REGS_BANKS : 5; >> + } > > Static analysis warnings make no sense until you provide a reliable way > to trigger the problem on real systems. > >> for (bank = 0; bank < nbank; bank++) >> chips->regs[bank] = gpio_base + offset_array[bank]; >> > > Thanks, > Olek > I can only see the code at this time. And I see the following: 1. In some configurations CONFIG_ARCH_NR_GPIO value is 2048. So nbank value can be 64. 2. Previously, a patch was proposed that removes restrictions on the number of GPIOs (https://lore.kernel.org/all/cb540a9d73cad36d288664f8b275c6308a4a3168.1662116601.git.christophe.leroy@csgroup.eu/).
From: Aleksandr Mishin <amishin@t-argos.ru> Date: Thu, 28 Mar 2024 19:23:56 +0300 > > > 28.03.2024 18:27, Alexander Lobakin пишет: >> From: Aleksandr Mishin <amishin@t-argos.ru> >> Date: Thu, 28 Mar 2024 12:10:21 +0300 >> >>> In davinci_gpio_probe() accessing an element of array 'chips->regs' >>> of size 5 and >>> array 'offset_array' of size 5 can lead to a buffer overflow, since >>> the index >>> 'bank' can have an out of range value 63. >>> Fix this bug by limiting top index value. >>> >>> Found by Linux Verification Center (linuxtesting.org) with SVACE. >>> >>> Fixes: c809e37a3b5a ("gpio: davinci: Allocate the correct amount of >>> memory for controller") >>> Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru> >>> --- >>> drivers/gpio/gpio-davinci.c | 3 +++ >>> 1 file changed, 3 insertions(+) >>> >>> diff --git a/drivers/gpio/gpio-davinci.c b/drivers/gpio/gpio-davinci.c >>> index bb499e362912..b65df1f2b83f 100644 >>> --- a/drivers/gpio/gpio-davinci.c >>> +++ b/drivers/gpio/gpio-davinci.c >>> @@ -257,6 +257,9 @@ static int davinci_gpio_probe(struct >>> platform_device *pdev) >>> spin_lock_init(&chips->lock); >>> nbank = DIV_ROUND_UP(ngpio, 32); >>> + if (nbank > MAX_REGS_BANKS || nbank > 5) { >>> + nbank = MAX_REGS_BANKS < 5 ? MAX_REGS_BANKS : 5; >>> + } >> >> Static analysis warnings make no sense until you provide a reliable way >> to trigger the problem on real systems. >> >>> for (bank = 0; bank < nbank; bank++) >>> chips->regs[bank] = gpio_base + offset_array[bank]; >>> >> >> Thanks, >> Olek >> > > I can only see the code at this time. And I see the following: > 1. In some configurations CONFIG_ARCH_NR_GPIO value is 2048. So nbank > value can be 64. > 2. Previously, a patch was proposed that removes restrictions on the > number of GPIOs > (https://lore.kernel.org/all/cb540a9d73cad36d288664f8b275c6308a4a3168.1662116601.git.christophe.leroy@csgroup.eu/). > But no real hardware / device tree which declares such huge number of GPIOs, right? CONFIG_ARCH_NR_GPIO is architecture-specific. Davinci is a platform, not an architecture. If no Davinci board can have a number that would overflow, the fix doesn't make sense. Thanks, Olek
On Thu, Mar 28, 2024 at 04:27:24PM +0100, Alexander Lobakin wrote: > > diff --git a/drivers/gpio/gpio-davinci.c b/drivers/gpio/gpio-davinci.c > > index bb499e362912..b65df1f2b83f 100644 > > --- a/drivers/gpio/gpio-davinci.c > > +++ b/drivers/gpio/gpio-davinci.c > > @@ -257,6 +257,9 @@ static int davinci_gpio_probe(struct platform_device *pdev) > > spin_lock_init(&chips->lock); > > > > nbank = DIV_ROUND_UP(ngpio, 32); > > + if (nbank > MAX_REGS_BANKS || nbank > 5) { > > + nbank = MAX_REGS_BANKS < 5 ? MAX_REGS_BANKS : 5; > > + } > > Static analysis warnings make no sense until you provide a reliable way > to trigger the problem on real systems. This patch isn't correct, but we merge a few static checker fixes every day. regards, dan carpenter
diff --git a/drivers/gpio/gpio-davinci.c b/drivers/gpio/gpio-davinci.c index bb499e362912..b65df1f2b83f 100644 --- a/drivers/gpio/gpio-davinci.c +++ b/drivers/gpio/gpio-davinci.c @@ -257,6 +257,9 @@ static int davinci_gpio_probe(struct platform_device *pdev) spin_lock_init(&chips->lock); nbank = DIV_ROUND_UP(ngpio, 32); + if (nbank > MAX_REGS_BANKS || nbank > 5) { + nbank = MAX_REGS_BANKS < 5 ? MAX_REGS_BANKS : 5; + } for (bank = 0; bank < nbank; bank++) chips->regs[bank] = gpio_base + offset_array[bank];
In davinci_gpio_probe() accessing an element of array 'chips->regs' of size 5 and array 'offset_array' of size 5 can lead to a buffer overflow, since the index 'bank' can have an out of range value 63. Fix this bug by limiting top index value. Found by Linux Verification Center (linuxtesting.org) with SVACE. Fixes: c809e37a3b5a ("gpio: davinci: Allocate the correct amount of memory for controller") Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru> --- drivers/gpio/gpio-davinci.c | 3 +++ 1 file changed, 3 insertions(+)