Linux kernel vhost IOTLB table overflow (CVE-2026-74713)
CVE-2026-74713 Published on August 22, 2026
vhost_iotlb: bound map allocation in add_range
In the Linux kernel, the following vulnerability has been resolved:
vhost_iotlb: bound map allocation in add_range
vhost_iotlb_add_range_ctx() only retires an old entry when the table
has a non-zero limit, has exactly reached that limit and has
VHOST_IOTLB_FLAG_RETIRE set. Non-retiring tables can keep allocating
entries after reaching their configured limit.
Existing vhost devices allocate their IOTLB with max_iotlb_entries from
vhost.c, which defaults to 2048 and is tunable by module parameter. Use
the caller-provided limit at the allocation point instead of adding a
separate default in the common IOTLB helper, and reject non-positive
values in vhost paths that can report an error.
Other vhost IOTLB users should not create zero-limit tables when entries
can be populated from userspace or guest-controlled requests. Add
caller-side max_iotlb_entries parameters for mlx5 vDPA, VDUSE and
vhost-vDPA. Reject non-positive VDUSE and vhost-vDPA values, and require
at least two entries for vdpa_sim and mlx5 vDPA paths that install
full-range mappings, since those mappings are split into two IOTLB
entries.
Handle full-range mappings in the common helper by checking that the
IOTLB can hold both split entries before inserting the first half. This
avoids returning an error after leaving a half mapping behind.
When the table is full, keep the existing retire behavior for retiring
tables and return -ENOSPC for non-retiring tables. Reuse the retired map
node instead of freeing it and allocating a replacement, so a stream of
IOTLB updates cannot keep forcing GFP_ATOMIC allocations after the table
has reached its limit. If a zero-limit IOTLB still reaches the common
helper, treat it as a configuration error and return -EINVAL.
I found this bug myself, though the patch was written with AI assistance.
Products Associated with CVE-2026-74713
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Affected Versions
Linux:- Version 0bbe30668d89ec8a309f28ced6d092c90fb23e8c and below ae128dd19040ee06a4f8143c7ced4d18080d7a9a is affected.
- Version 0bbe30668d89ec8a309f28ced6d092c90fb23e8c and below 1ed35ac7f3fe2b4396bdd29ac3a7f0ebc0829e94 is affected.
- Version 5.7 is affected.
- Before 5.7 is unaffected.
- Version 7.1.9, <= 7.1.* is unaffected.
- Version 7.2, <= * is unaffected.