{"id":"CVE-2026-98588","summary":"bpf, sockmap: Reject max_entries \u003e INT_MAX in sock_map_alloc","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, sockmap: Reject max_entries \u003e INT_MAX in sock_map_alloc\n\nsock_map_alloc() only rejects max_entries == 0 and otherwise allows any\nu32 value.  sock_map_free() then walks the sks[] array with a signed int\niterator:\n\n\tint i;\n\tfor (i = 0; i \u003c stab-\u003emap.max_entries; i++)\n\t\tstruct sock **psk = &stab-\u003esks[i];\n\nWhen a SOCKMAP is created with max_entries = 0xffffffff (UINT_MAX), the\nallocation of 32 GiB can succeed on large-memory hosts.  During free the\ncounter reaches 0x80000000, wraps to INT_MIN, is sign-extended by movslq\nand turned into a ~16 GiB negative offset from stab-\u003esks, pointing far\nbelow the allocation.\n\nThe faulting access is an xchg() write in sock_map_free().  Without\nKASAN, the same out-of-bounds write can fault on an unmapped vmalloc page\nor corrupt an unrelated allocation if that vmalloc address is populated.\nOn a KASAN kernel with CONFIG_KASAN_VMALLOC=y, the shadow check for that\naddress hits an unmapped shadow page and oopses first:\n\n  BUG: unable to handle page fault for address: fffff521b59c5a00\n  RIP: 0010:kasan_check_range+0x107/0x190\n  Call Trace:\n   sock_map_free+0x93/0x190\n   map_create+0x68d/0xb30\n   __sys_bpf+0x21e/0x2e70\n\nVmcore confirmed stab-\u003emap.max_entries == 0xffffffff, stab-\u003esks ==\n0xffffc911ace2d000, and the faulting address sks + (s64)INT_MIN * 8\nexactly at 0xffffc90dace2d000.  The same buggy path is reached on the\nnormal close()/bpf_map_free_deferred() path whenever such a map is\ndestroyed.\n\nsock_map_alloc() used to bound its allocation size through\nbpf_map_charge_init(), but the bound was dropped when rlimit-based memory\naccounting was removed.  Reject max_entries \u003e INT_MAX at creation time so\nthe signed iterator in sock_map_free() never sees a value that would\noverflow.\n\nTriggered by syzkaller and reproduced on both a 6.6-based KASAN kernel\nand the upstream v7.3-rc2 kernel.","modified":"2026-10-20T02:30:18.052262529Z","published":"2026-10-18T15:19:00.934Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98588.json","cna_assigner":"Linux"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/814a81c842bd88f6bd8a4ce550d560df071a5d03"},{"type":"WEB","url":"https://git.kernel.org/stable/c/909f761868fda329dc69130ef9eb5b5795bcdf00"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ba7d627dbc67d62df2fa66d7b41e743c3ace0ec8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c56191af3a578b9cc265fa3bd5fc0752c59c1781"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cc70972ddbf0e3398f2f32624d31db78594d50d8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cea597519b9ca6d691c98d92460ead8ece2a07af"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f4a73f49e256bd835368504462be3b57b03febff"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98588.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98588"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0d2c4f9640501ff57ba0be1f5644a02c29a02fa1"},{"fixed":"f4a73f49e256bd835368504462be3b57b03febff"},{"fixed":"c56191af3a578b9cc265fa3bd5fc0752c59c1781"},{"fixed":"909f761868fda329dc69130ef9eb5b5795bcdf00"},{"fixed":"cc70972ddbf0e3398f2f32624d31db78594d50d8"},{"fixed":"cea597519b9ca6d691c98d92460ead8ece2a07af"},{"fixed":"ba7d627dbc67d62df2fa66d7b41e743c3ace0ec8"},{"fixed":"814a81c842bd88f6bd8a4ce550d560df071a5d03"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98588.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.222"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.189"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.158"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.112"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.55"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.9"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98588.json"}}],"schema_version":"1.9.0"}