Messages in this thread | | | Subject | Re: Limits for ION Memory Allocator | From | Laura Abbott <> | Date | Wed, 24 Jul 2019 15:36:57 -0400 |
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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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