{"id":"AZL-108951","summary":"CVE-2026-98588 affecting package kernel 6.6.157.1-1","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":"2026-10-19T14:16:50.091494632Z","published":"2026-10-18T16:17:11Z","upstream":["CVE-2026-98588"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98588"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.157.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-108951.json"}}],"schema_version":"1.9.0"}