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| author | Michael S. Tsirkin <mst@redhat.com> | 2016-08-01 23:20:53 +0300 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2016-08-02 16:54:28 +0300 |
| commit | ec33d031a14b3c5dd516627139c9550350dbba3e (patch) | |
| tree | 7f8913c2a0b5524836f31385f0a879e1ec6ed7ce /drivers/vhost | |
| parent | 6b1e6cc7855b09a0a9bfa1d9f30172ba366f161c (diff) | |
| download | lwn-ec33d031a14b3c5dd516627139c9550350dbba3e.tar.gz lwn-ec33d031a14b3c5dd516627139c9550350dbba3e.zip | |
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>
Diffstat (limited to 'drivers/vhost')
| -rw-r--r-- | drivers/vhost/vhost.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index d02c1614921f..c6f2d89c0e97 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -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; |