{"id":"CVE-2026-89557","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-89557","summary":"md: do overflow check for sb->bblog_shift in super_1_load()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nmd: do overflow check for sb->bblog_shift in super_1_load()\n\nIn super_1_load(), sb->bblog_shift is an __u8 type value loaded from on-\ndisk superblock. It is used for badblocks API badblocks_set() by the\nfollowing sequence,\n\n 1930   rdev->badblocks.shift = sb->bblog_shift;\n 1931   for (i = 0 ; i < (sectors << (9-3)) ; i++, bbp++) {\n 1932           u64 bb = le64_to_cpu(*bbp);\n 1933           int count = bb & (0x3ff);\n 1934           u64 sector = bb >> 10;\n 1935           sector <<= sb->bblog_shift;\n 1936           count <<= sb->bblog_shift;\n 1937           if (bb + 1 == 0)\n 1938                   break;\n 1939           if (!badblocks_set(&rdev->badblocks, sector, count, 1))\n 1940                   return -EINVAL;\n 1941   }\n\nbb->bblog_shit is in range of 0-255, variable sector is 64bit width, for\nan invalid bb->bblog_shit, it is possible to make sector be overflowed\nby the following calculation,\n 1935           sector <<= sb->bblog_shift;\nThen in turn when call badblocks_set() at line 1939 with the invalid\nrdev->badblocks.shift set at line 1930, may result an overflow inside\n_badblocks_clear() in block/badblocks.c.\n\nAlthough there are many places to call badblocks APIs, the non-zero\nshift value is only used in super_1_load(), other places always use 0 as\nthe shift value. Therefore it is unnecessary to do a general shift value\noverflow check inside badblock API, and just check here as the caller.\n\nThis may avoid unnecessary check, make the badblocks API code more simple\nand elegant.","published":"2026-09-11T19:44:29.857Z","modified":"2026-09-14T03:46:14.013903422Z","cvss":{"score":7.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.12.109"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/35d522bd32462afcf1981dab6da8a9256c26c1e0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3b097416b4cff77285c1f472fc2c4058d8a7554f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/75d15738fd33a782606d0dc80cfeff47edf2ddd8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/df7d4d011d5ace20699ea948712f09f9ac08924f"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89557.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89557"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-14T03:46:14.013903422Z"}}