{"id":"CVE-2026-98801","title":"net: restrict SO_RESERVE_MEM to TCP sockets and cap max value","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: restrict SO_RESERVE_MEM to TCP sockets and cap max value\n\nCommit 2bb2f5fb21b0 (\"net: add new socket option SO_RESERVE_MEM\") and\ncommit d00c8ee31729 (\"net: fix poss…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 2bb2f5fb21b0486ff69b7b4a1fe03a760527d133 < 492e04f9a00f3cc88a1f6899417b10f3019a624e","Linux >= 2bb2f5fb21b0486ff69b7b4a1fe03a760527d133 < 5069ce898148bd799395c5a464e006cbb840f188","Linux >= 2bb2f5fb21b0486ff69b7b4a1fe03a760527d133 < a467b05b201b5c26be52ed3081992fa9c0387648","Linux >= 2bb2f5fb21b0486ff69b7b4a1fe03a760527d133 < 37e02c42a00be692c06343e11779aadc45f45971","Linux 5.16"],"published":"2026-10-18","updated":"2026-10-18","sourceUpdated":"2026-10-18T15:48:47.171Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98801","references":[{"url":"https://git.kernel.org/stable/c/492e04f9a00f3cc88a1f6899417b10f3019a624e"},{"url":"https://git.kernel.org/stable/c/5069ce898148bd799395c5a464e006cbb840f188"},{"url":"https://git.kernel.org/stable/c/a467b05b201b5c26be52ed3081992fa9c0387648"},{"url":"https://git.kernel.org/stable/c/37e02c42a00be692c06343e11779aadc45f45971"}],"tags":["cve.org"],"ingestedAt":"2026-10-18T16:47:32.481Z","slug":"CVE-2026-98801","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet: restrict SO_RESERVE_MEM to TCP sockets and cap max value\n\nCommit 2bb2f5fb21b0 (\"net: add new socket option SO_RESERVE_MEM\") and\ncommit d00c8ee31729 (\"net: fix possible NULL deref in sock_reserve_memory\")\nonly checked sk_has_account(sk), which is true for both TCP and UDP\nsockets.\n\nHowever, SO_RESERVE_MEM and sk_unused_reserved_mem() are currently only\nsupported by TCP:\n- On UDP sockets, sk->sk_forward_alloc is protected by\n  sk->sk_receive_queue.lock, whereas sock_reserve_memory() and\n  sock_release_reserved_memory() only acquire lock_sock(sk). Concurrent\n  UDP packet reception/release and setsockopt(SO_RESERVE_MEM) corrupt\n  sk_forward_alloc and memcg accounting.\n- udp_rmem_release() reclaims excess sk_forward_alloc without\n  accounting for sk_unused_reserved_mem(sk).\n\nRestrict sock_reserve_memory() to TCP sockets (sk_is_tcp(sk)) for now.\nSupporting SO_RESERVE_MEM for UDP (acquiring sk_receive_queue.lock and\nhonoring sk_unused_reserved_mem() in udp_rmem_release()) can be done in\na future net-next series if needed.\n\nIn addition, reject val > SZ_1G with -EINVAL in\nsk_setsockopt(SO_RESERVE_MEM). Without an upper bound, values near\nINT_MAX cause sk_mem_pages(delta) and (pages << PAGE_SHIFT) to overflow\n32-bit signed int, corrupting sk->sk_forward_alloc and\nsk->sk_reserved_mem. Using a page-aligned cap (SZ_1G) ensures that the\npage-rounded sk->sk_reserved_mem reported by getsockopt(SO_RESERVE_MEM)\ncan always be passed back to setsockopt(SO_RESERVE_MEM).\n\n## Affected\n\n- `Linux >= 2bb2f5fb21b0486ff69b7b4a1fe03a760527d133 < 492e04f9a00f3cc88a1f6899417b10f3019a624e`\n- `Linux >= 2bb2f5fb21b0486ff69b7b4a1fe03a760527d133 < 5069ce898148bd799395c5a464e006cbb840f188`\n- `Linux >= 2bb2f5fb21b0486ff69b7b4a1fe03a760527d133 < a467b05b201b5c26be52ed3081992fa9c0387648`\n- `Linux >= 2bb2f5fb21b0486ff69b7b4a1fe03a760527d133 < 37e02c42a00be692c06343e11779aadc45f45971`\n- `Linux 5.16`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}