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vhost: detect 32 bit integer wrap around 

Detect and fail early if long wrap around is triggered.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2016-08-01 23:20:53 +03:00
parent 6b1e6cc785
commit ec33d031a1
1 changed files with 14 additions and 2 deletions
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16
drivers/vhost/vhost.c
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@ -657,6 +657,12 @@ static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
(sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8);
}
static bool vhost_overflow(u64 uaddr, u64 size)
{
/* Make sure 64 bit math will not overflow. */
return uaddr > ULONG_MAX || size > ULONG_MAX || uaddr > ULONG_MAX - size;
}
/* Caller should have vq mutex and device mutex. */
static int vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
int log_all)
@ -669,9 +675,11 @@ static int vq_memory_access_ok(void __user *log_base, struct vhost_umem *umem,
list_for_each_entry(node, &umem->umem_list, link) {
unsigned long a = node->userspace_addr;
if (node->size > ULONG_MAX)
if (vhost_overflow(node->userspace_addr, node->size))
return 0;
else if (!access_ok(VERIFY_WRITE, (void __user *)a,
if (!access_ok(VERIFY_WRITE, (void __user *)a,
node->size))
return 0;
else if (log_all && !log_access_ok(log_base,
@ -913,6 +921,10 @@ static int umem_access_ok(u64 uaddr, u64 size, int access)
{
unsigned long a = uaddr;
/* Make sure 64 bit math will not overflow. */
if (vhost_overflow(uaddr, size))
return -EFAULT;
if ((access & VHOST_ACCESS_RO) &&
!access_ok(VERIFY_READ, (void __user *)a, size))
return -EFAULT;