CODEWITHSUNDEEP
clinux-kernel
Fadeway
Fadeway

Reputation: 588

Safe handling of userspace pointers in a driver?

I'm writing an ioctl driver that needs to read and write data to userspace. For visualization, here's a typical argument that goes in a driver call:

typedef struct {
unsigned int* src;
unsigned int* dst;
unsigned int buffer_size;
unsigned int key[8];
} aes_data

I'm not very well-versed in how virtual memory works, but I think there's a risk here. The userspace process could have provided a pointer to memory it does not own. The provided buffer size could cause an overflow into the memory of some other process as well. How do I handle these userspace pointers responsibly in my driver?

Upvotes: 1

Views: 94

Answers (1)

BЈовић
BЈовић

Reputation: 64223

How do I handle these userspace pointers responsibly in my driver?

You don't, simply because there are no ways to check if the pointers points to anything valid. It is up to the user of the ioctl() to provide proper parameters. If they fail to do that, then tough luck for them.

Upvotes: 1

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