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CVE-2026-90435: RDMA/mlx5: Fix integer overflow of user QP buffer size

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-17 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx5: Fix integer overflow of user QP buffer size set_user_buf_size() computes the QP buffer size by left-shifting the user-supplied rq.wqe_cnt and rq.wqe_shift values as signed integers. A sufficiently large rq.wqe_cnt causes signed integer overflow, which is undefined behavior, and yields a small or negative buf_size, causing ib_umem_get() to map a buffer smaller than the hardware will actually write into. Replace the shifts and addition with check_shl_overflow() and check_add_overflow(), rejecting invalid user inputs. Moreover, guard the identical shift computing qp->sq.offset in _create_user_qp() before set_user_buf_size() is reached.

Affected products

• Linux kernel: 3.11 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux kernel 7.3. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/42fb8aefffff5b458aaa66803364a16e0ea44129
• https://git.kernel.org/stable/c/5b6cfc6d7ff0959dd9766fdc24286a253b59ca77
• https://git.kernel.org/stable/c/c845e5e05140ea1bc64a5b1107942d93c876034d
• https://git.kernel.org/stable/c/ccce6b7ef1d7efc59ccba3421e1339c6e63a3d20
• https://git.kernel.org/stable/c/d7fa2ff72ad1861eac194a4e0075d504ba8c246e
• https://git.kernel.org/stable/c/d99622e40aaa910ade681dfd4dc0fa240a011331
• https://git.kernel.org/stable/c/dec47e4b0fe34afdf38caa72b4408ba95502e5de
• https://git.kernel.org/stable/c/f917707f0de0832b8ab582391b1f64e549995c6c

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