{"cve":"CVE-2026-89557","nvd":{"published":"2026-09-11T20:19:39.403","modified":"2026-10-19T09:17:51.190","status":"Received","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":[],"references":["https://git.kernel.org/stable/c/0a03f9541c06fda64301dcf94f376f07ce2cc396","https://git.kernel.org/stable/c/323f3a056dbccb39a642ebde642044a680f3a6d6","https://git.kernel.org/stable/c/35d522bd32462afcf1981dab6da8a9256c26c1e0","https://git.kernel.org/stable/c/3b097416b4cff77285c1f472fc2c4058d8a7554f","https://git.kernel.org/stable/c/573fb68105fdc6a127ba6069e58a0d2aff3c9f93"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:53:43.293028046+00:00"},"epss":{"cve":"CVE-2026-89557","score":0.00169,"percentile":0.06197,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}