* [PATCH] ppc/pnv: Fix potential overflow in I2C model
@ 2023-11-09 8:05 Cédric Le Goater
2023-11-09 8:12 ` Philippe Mathieu-Daudé
2023-11-09 15:02 ` Peter Maydell
0 siblings, 2 replies; 6+ messages in thread
From: Cédric Le Goater @ 2023-11-09 8:05 UTC (permalink / raw)
To: qemu-devel, qemu-ppc
Cc: Frédéric Barrat, Nicholas Piggin, Cédric Le Goater,
Glenn Miles
Coverity warns that "i2c_bus_busy(i2c->busses[i]) << i" might overflow
because the expression is evaluated using 32-bit arithmetic and then
used in a context expecting a uint64_t.
Fixes: Coverity CID 1523918
Cc: Glenn Miles <milesg@linux.vnet.ibm.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
---
hw/ppc/pnv_i2c.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/hw/ppc/pnv_i2c.c b/hw/ppc/pnv_i2c.c
index f75e59e70977..ab73c59f7704 100644
--- a/hw/ppc/pnv_i2c.c
+++ b/hw/ppc/pnv_i2c.c
@@ -437,7 +437,7 @@ static uint64_t pnv_i2c_xscom_read(void *opaque, hwaddr addr,
case I2C_PORT_BUSY_REG: /* compute busy bit for each port */
val = 0;
for (i = 0; i < i2c->num_busses; i++) {
- val |= i2c_bus_busy(i2c->busses[i]) << i;
+ val |= (uint64_t) i2c_bus_busy(i2c->busses[i]) << i;
}
break;
--
2.41.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] ppc/pnv: Fix potential overflow in I2C model
2023-11-09 8:05 [PATCH] ppc/pnv: Fix potential overflow in I2C model Cédric Le Goater
@ 2023-11-09 8:12 ` Philippe Mathieu-Daudé
2023-11-09 15:02 ` Peter Maydell
1 sibling, 0 replies; 6+ messages in thread
From: Philippe Mathieu-Daudé @ 2023-11-09 8:12 UTC (permalink / raw)
To: Cédric Le Goater, qemu-devel, qemu-ppc
Cc: Frédéric Barrat, Nicholas Piggin, Glenn Miles
On 9/11/23 09:05, Cédric Le Goater wrote:
> Coverity warns that "i2c_bus_busy(i2c->busses[i]) << i" might overflow
> because the expression is evaluated using 32-bit arithmetic and then
> used in a context expecting a uint64_t.
>
> Fixes: Coverity CID 1523918
> Cc: Glenn Miles <milesg@linux.vnet.ibm.com>
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
> hw/ppc/pnv_i2c.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/ppc/pnv_i2c.c b/hw/ppc/pnv_i2c.c
> index f75e59e70977..ab73c59f7704 100644
> --- a/hw/ppc/pnv_i2c.c
> +++ b/hw/ppc/pnv_i2c.c
> @@ -437,7 +437,7 @@ static uint64_t pnv_i2c_xscom_read(void *opaque, hwaddr addr,
> case I2C_PORT_BUSY_REG: /* compute busy bit for each port */
> val = 0;
> for (i = 0; i < i2c->num_busses; i++) {
> - val |= i2c_bus_busy(i2c->busses[i]) << i;
> + val |= (uint64_t) i2c_bus_busy(i2c->busses[i]) << i;
Alternatively:
val = deposit64(val, i, 1, i2c_bus_busy(i2c->busses[i]));
> }
> break;
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] ppc/pnv: Fix potential overflow in I2C model
2023-11-09 8:05 [PATCH] ppc/pnv: Fix potential overflow in I2C model Cédric Le Goater
2023-11-09 8:12 ` Philippe Mathieu-Daudé
@ 2023-11-09 15:02 ` Peter Maydell
2023-11-09 15:54 ` Cédric Le Goater
1 sibling, 1 reply; 6+ messages in thread
From: Peter Maydell @ 2023-11-09 15:02 UTC (permalink / raw)
To: Cédric Le Goater
Cc: qemu-devel, qemu-ppc, Frédéric Barrat, Nicholas Piggin,
Glenn Miles
On Thu, 9 Nov 2023 at 08:06, Cédric Le Goater <clg@kaod.org> wrote:
>
> Coverity warns that "i2c_bus_busy(i2c->busses[i]) << i" might overflow
> because the expression is evaluated using 32-bit arithmetic and then
> used in a context expecting a uint64_t.
>
> Fixes: Coverity CID 1523918
> Cc: Glenn Miles <milesg@linux.vnet.ibm.com>
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
> hw/ppc/pnv_i2c.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/ppc/pnv_i2c.c b/hw/ppc/pnv_i2c.c
> index f75e59e70977..ab73c59f7704 100644
> --- a/hw/ppc/pnv_i2c.c
> +++ b/hw/ppc/pnv_i2c.c
> @@ -437,7 +437,7 @@ static uint64_t pnv_i2c_xscom_read(void *opaque, hwaddr addr,
> case I2C_PORT_BUSY_REG: /* compute busy bit for each port */
> val = 0;
> for (i = 0; i < i2c->num_busses; i++) {
> - val |= i2c_bus_busy(i2c->busses[i]) << i;
> + val |= (uint64_t) i2c_bus_busy(i2c->busses[i]) << i;
> }
> break;
Should the device's realize function also impose a max
limit on the num-busses property? There doesn't seem to be
anything preventing a caller from setting it to a big
number like 128, which would then be UB here.
Style nit: casts shouldn't have a space after them before
the thing they're casting.
thanks
-- PMM
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] ppc/pnv: Fix potential overflow in I2C model
2023-11-09 15:02 ` Peter Maydell
@ 2023-11-09 15:54 ` Cédric Le Goater
2023-11-09 16:07 ` Peter Maydell
2023-11-09 18:51 ` Philippe Mathieu-Daudé
0 siblings, 2 replies; 6+ messages in thread
From: Cédric Le Goater @ 2023-11-09 15:54 UTC (permalink / raw)
To: Peter Maydell
Cc: qemu-devel, qemu-ppc, Frédéric Barrat, Nicholas Piggin,
Glenn Miles, Philippe Mathieu-Daudé
On 11/9/23 16:02, Peter Maydell wrote:
> On Thu, 9 Nov 2023 at 08:06, Cédric Le Goater <clg@kaod.org> wrote:
>>
>> Coverity warns that "i2c_bus_busy(i2c->busses[i]) << i" might overflow
>> because the expression is evaluated using 32-bit arithmetic and then
>> used in a context expecting a uint64_t.
>>
>> Fixes: Coverity CID 1523918
>> Cc: Glenn Miles <milesg@linux.vnet.ibm.com>
>> Signed-off-by: Cédric Le Goater <clg@kaod.org>
>> ---
>> hw/ppc/pnv_i2c.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/hw/ppc/pnv_i2c.c b/hw/ppc/pnv_i2c.c
>> index f75e59e70977..ab73c59f7704 100644
>> --- a/hw/ppc/pnv_i2c.c
>> +++ b/hw/ppc/pnv_i2c.c
>> @@ -437,7 +437,7 @@ static uint64_t pnv_i2c_xscom_read(void *opaque, hwaddr addr,
>> case I2C_PORT_BUSY_REG: /* compute busy bit for each port */
>> val = 0;
>> for (i = 0; i < i2c->num_busses; i++) {
>> - val |= i2c_bus_busy(i2c->busses[i]) << i;
>> + val |= (uint64_t) i2c_bus_busy(i2c->busses[i]) << i;
>> }
>> break;
>
> Should the device's realize function also impose a max
> limit on the num-busses property? There doesn't seem to be
> anything preventing a caller from setting it to a big
> number like 128, which would then be UB here.
yes. I will add an assert(i2c->num_busses < 64). The current max
is 16 for POWER10.
> Style nit: casts shouldn't have a space after them before
> the thing they're casting.
yep.
I prefer the cast method than the deposit call. Philippe, I hope you
don't mind ?
Thanks,
C.
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] ppc/pnv: Fix potential overflow in I2C model
2023-11-09 15:54 ` Cédric Le Goater
@ 2023-11-09 16:07 ` Peter Maydell
2023-11-09 18:51 ` Philippe Mathieu-Daudé
1 sibling, 0 replies; 6+ messages in thread
From: Peter Maydell @ 2023-11-09 16:07 UTC (permalink / raw)
To: Cédric Le Goater
Cc: qemu-devel, qemu-ppc, Frédéric Barrat, Nicholas Piggin,
Glenn Miles, Philippe Mathieu-Daudé
On Thu, 9 Nov 2023 at 15:54, Cédric Le Goater <clg@kaod.org> wrote:
>
> On 11/9/23 16:02, Peter Maydell wrote:
> > On Thu, 9 Nov 2023 at 08:06, Cédric Le Goater <clg@kaod.org> wrote:
> >>
> >> Coverity warns that "i2c_bus_busy(i2c->busses[i]) << i" might overflow
> >> because the expression is evaluated using 32-bit arithmetic and then
> >> used in a context expecting a uint64_t.
> >>
> >> Fixes: Coverity CID 1523918
> >> Cc: Glenn Miles <milesg@linux.vnet.ibm.com>
> >> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> >> ---
> >> hw/ppc/pnv_i2c.c | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/hw/ppc/pnv_i2c.c b/hw/ppc/pnv_i2c.c
> >> index f75e59e70977..ab73c59f7704 100644
> >> --- a/hw/ppc/pnv_i2c.c
> >> +++ b/hw/ppc/pnv_i2c.c
> >> @@ -437,7 +437,7 @@ static uint64_t pnv_i2c_xscom_read(void *opaque, hwaddr addr,
> >> case I2C_PORT_BUSY_REG: /* compute busy bit for each port */
> >> val = 0;
> >> for (i = 0; i < i2c->num_busses; i++) {
> >> - val |= i2c_bus_busy(i2c->busses[i]) << i;
> >> + val |= (uint64_t) i2c_bus_busy(i2c->busses[i]) << i;
> >> }
> >> break;
> >
> > Should the device's realize function also impose a max
> > limit on the num-busses property? There doesn't seem to be
> > anything preventing a caller from setting it to a big
> > number like 128, which would then be UB here.
>
> yes. I will add an assert(i2c->num_busses < 64). The current max
> is 16 for POWER10.
We generally make that kind of "property out of range" check
be an error_setg()-and-return, rather than an assert.
thanks
-- PMM
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] ppc/pnv: Fix potential overflow in I2C model
2023-11-09 15:54 ` Cédric Le Goater
2023-11-09 16:07 ` Peter Maydell
@ 2023-11-09 18:51 ` Philippe Mathieu-Daudé
1 sibling, 0 replies; 6+ messages in thread
From: Philippe Mathieu-Daudé @ 2023-11-09 18:51 UTC (permalink / raw)
To: Cédric Le Goater, Peter Maydell
Cc: qemu-devel, qemu-ppc, Frédéric Barrat, Nicholas Piggin,
Glenn Miles
On 9/11/23 16:54, Cédric Le Goater wrote:
> On 11/9/23 16:02, Peter Maydell wrote:
>> On Thu, 9 Nov 2023 at 08:06, Cédric Le Goater <clg@kaod.org> wrote:
>>>
>>> Coverity warns that "i2c_bus_busy(i2c->busses[i]) << i" might overflow
>>> because the expression is evaluated using 32-bit arithmetic and then
>>> used in a context expecting a uint64_t.
>>>
>>> Fixes: Coverity CID 1523918
>>> Cc: Glenn Miles <milesg@linux.vnet.ibm.com>
>>> Signed-off-by: Cédric Le Goater <clg@kaod.org>
>>> ---
>>> hw/ppc/pnv_i2c.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/hw/ppc/pnv_i2c.c b/hw/ppc/pnv_i2c.c
>>> index f75e59e70977..ab73c59f7704 100644
>>> --- a/hw/ppc/pnv_i2c.c
>>> +++ b/hw/ppc/pnv_i2c.c
>>> @@ -437,7 +437,7 @@ static uint64_t pnv_i2c_xscom_read(void *opaque,
>>> hwaddr addr,
>>> case I2C_PORT_BUSY_REG: /* compute busy bit for each port */
>>> val = 0;
>>> for (i = 0; i < i2c->num_busses; i++) {
>>> - val |= i2c_bus_busy(i2c->busses[i]) << i;
>>> + val |= (uint64_t) i2c_bus_busy(i2c->busses[i]) << i;
>>> }
>>> break;
>>
>> Should the device's realize function also impose a max
>> limit on the num-busses property? There doesn't seem to be
>> anything preventing a caller from setting it to a big
>> number like 128, which would then be UB here.
>
> yes. I will add an assert(i2c->num_busses < 64). The current max
> is 16 for POWER10.
>
>> Style nit: casts shouldn't have a space after them before
>> the thing they're casting.
>
> yep.
>
> I prefer the cast method than the deposit call. Philippe, I hope you
> don't mind ?
Matter of taste, I don't mind ¯\_(ツ)_/¯
^ permalink raw reply [flat|nested] 6+ messages in thread
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2023-11-09 8:05 [PATCH] ppc/pnv: Fix potential overflow in I2C model Cédric Le Goater
2023-11-09 8:12 ` Philippe Mathieu-Daudé
2023-11-09 15:02 ` Peter Maydell
2023-11-09 15:54 ` Cédric Le Goater
2023-11-09 16:07 ` Peter Maydell
2023-11-09 18:51 ` Philippe Mathieu-Daudé
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