CVE-2026-93105esp: do not unref managed frag pages in esp_ssg_unref()

Official description

In the Linux kernel, the following vulnerability has been resolved: esp: do not unref managed frag pages in esp_ssg_unref() esp_ssg_unref() releases the page references held on the source scatterlist after the AEAD operation completes. It calls skb_page_unref() on every frag page for an out-of-place transform (req->src != req->dst), and in the error path of esp_output_tail() (already_unref == true) on the request's own scatterlist. This is wrong when the skb carries managed frags (SKBFL_MANAGED_FRAG_REFS). Managed frags are owned by a zerocopy ubuf and the skb does not hold a per-frag page reference; io_uring SEND_ZC with a registered buffer attaches the bvec pages this way via io_sg_from_iter(). The rest of the stack honours this invariant: skb_release_data() skips the per-frag unref when SKBFL_MANAGED_FRAG_REFS is set, and skb_zcopy_managed() is the guard used at the other unref sites. esp_ssg_unref() is missing that guard, so for a managed-frag skb it drops a page reference the skb never acquired. This can underflow the page reference count and free a page that is still in use. Guard the function with skb_zcopy_managed() so both unref paths are skipped for managed-frag skbs, matching skb_release_data().

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/cb375965800d474c0281a2e92c43c724fce9f463
• https://git.kernel.org/stable/c/201bdf10ae92e7cbd524adf8c0323e2a963d5fd7
• https://git.kernel.org/stable/c/3ec55f0c8a6a543cf660584d1346e11f6311ee59
• https://git.kernel.org/stable/c/1ad6456898f6e6cf58be83bdb607acb1119a9cd1
• https://git.kernel.org/stable/c/26b6b14c7a0368e317a1e9fb5144ebe6f8d495cf
• https://git.kernel.org/stable/c/21697720ff43b8dfa25b8e8d9ca7f56f4597fc80