Messages in this thread Patch in this message | | | From | Xuewen Yan <> | Date | Tue, 15 Aug 2023 14:56:49 +0800 | Subject | Re: [PATCH] PM: QOS: Always use "kstrtos32_from_user()" in cpu_latency_qos_write() |
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Hi rafael
What do you think of this patch?
# echo 500 > /dev/cpu_dma_latency [T4893] write: qos value=170930229 [T4893] write: count value=4
the value is 170930229 is because it's hex is 0x0A303035, It is exactly the "500\0"
# echo 200> /dev/cpu_dma_latency [T4893] write: qos value=170930226 [T4893] write: count value=4
the value is 170930226 is because it's hex is 0x0A303032, It is exactly the "200\0"
Thanks!
On Mon, Aug 7, 2023 at 3:17 PM Xuewen Yan <xuewen.yan@unisoc.com> wrote: > > In cpu_latency_qos_write, there is a judgment on whether the count > value is equal to sizeof(s32). This means that when user write 100~999, > it would get error value because it would call the "copy_from_user()" > instead of "kstrtos32". > Just like: > > # echo 500 > /dev/cpu_dma_latency > [T4893] write: qos value=170930229 > [T4893] write: count value=4 > > [T4893] write: qos value=170930226 > [T4893] write: count value=4 > > To prevent this happening, delete the "copy_from_user()" and > always use "kstrtos32_from_user()". > > Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com> > --- > kernel/power/qos.c | 14 ++++---------- > 1 file changed, 4 insertions(+), 10 deletions(-) > > diff --git a/kernel/power/qos.c b/kernel/power/qos.c > index 782d3b41c1f3..21a2f873e921 100644 > --- a/kernel/power/qos.c > +++ b/kernel/power/qos.c > @@ -379,17 +379,11 @@ static ssize_t cpu_latency_qos_write(struct file *filp, const char __user *buf, > size_t count, loff_t *f_pos) > { > s32 value; > + int ret; > > - if (count == sizeof(s32)) { > - if (copy_from_user(&value, buf, sizeof(s32))) > - return -EFAULT; > - } else { > - int ret; > - > - ret = kstrtos32_from_user(buf, count, 16, &value); > - if (ret) > - return ret; > - } > + ret = kstrtos32_from_user(buf, count, 16, &value); > + if (ret) > + return ret; > > cpu_latency_qos_update_request(filp->private_data, value); > > -- > 2.25.1 >
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