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CVE-2026-90415: RDMA/cxgb4: free STAG index when TPT entry write fails

• Severity: unknown
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% 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/cxgb4: free STAG index when TPT entry write fails write_tpt_entry() allocates a new STAG index with c4iw_get_resource() and bumps stats.stag.cur before programming the entry. When write_adapter_mem() fails, it returns the error without releasing the index or reversing the statistic. No MR is inserted into rhp->mrs, so deregistration never reclaims it, leaking the index until device teardown. Record whether this call allocated the index and, on a failed write, return it to tpt_table and decrement stats.stag.cur. Key the rollback on both the write error and that flag, not the error alone: a non-reset update carries a caller-owned STAG that this call did not allocate and must not free.

Affected products

• Linux kernel: 3.5 — 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/2f17ca7ab5269ac2504e1039c3921373dccd7712
• https://git.kernel.org/stable/c/5a21e5114cec4cd3f8a2843d4c46bc49634d6e96
• https://git.kernel.org/stable/c/5fe4731bfbd8d83c4a14b4af3a27329969ce8a99
• https://git.kernel.org/stable/c/8f6976d635d190e3d7af7103daaa581cf1ccc12e
• https://git.kernel.org/stable/c/9eeafcda1d6c11f0eec532243c4e96ec8c632bd7
• https://git.kernel.org/stable/c/a2e37d1ab773be3cd26b1c19593ca2dbcece9c57
• https://git.kernel.org/stable/c/a64e2beb450179a5d43034af8d5476a11eac1486
• https://git.kernel.org/stable/c/fdfb5cea4bf070cdb31d997efd87bb684df041fd

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