{"id":"CVE-2026-89557","title":"md: do overflow check for sb->bblog_shift in super_1_load()","summary":"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 ba…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 2699b67223aca6b1450fc2f72e40fada952afc85 < 94c820d99a4305d4ded41a97ed37ec7d26c56e7f","Linux >= 2699b67223aca6b1450fc2f72e40fada952afc85 < 573fb68105fdc6a127ba6069e58a0d2aff3c9f93","Linux >= 2699b67223aca6b1450fc2f72e40fada952afc85 < 323f3a056dbccb39a642ebde642044a680f3a6d6","Linux >= 2699b67223aca6b1450fc2f72e40fada952afc85 < 0a03f9541c06fda64301dcf94f376f07ce2cc396","Linux >= 2699b67223aca6b1450fc2f72e40fada952afc85 < 75d15738fd33a782606d0dc80cfeff47edf2ddd8","Linux >= 2699b67223aca6b1450fc2f72e40fada952afc85 < 3b097416b4cff77285c1f472fc2c4058d8a7554f","Linux >= 2699b67223aca6b1450fc2f72e40fada952afc85 < df7d4d011d5ace20699ea948712f09f9ac08924f","Linux >= 2699b67223aca6b1450fc2f72e40fada952afc85 < 35d522bd32462afcf1981dab6da8a9256c26c1e0","Linux 3.1"],"published":"2026-09-11","updated":"2026-09-14","sourceUpdated":"2026-09-14T12:00:58.984Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89557","references":[{"url":"https://git.kernel.org/stable/c/94c820d99a4305d4ded41a97ed37ec7d26c56e7f"},{"url":"https://git.kernel.org/stable/c/573fb68105fdc6a127ba6069e58a0d2aff3c9f93"},{"url":"https://git.kernel.org/stable/c/323f3a056dbccb39a642ebde642044a680f3a6d6"},{"url":"https://git.kernel.org/stable/c/0a03f9541c06fda64301dcf94f376f07ce2cc396"},{"url":"https://git.kernel.org/stable/c/75d15738fd33a782606d0dc80cfeff47edf2ddd8"},{"url":"https://git.kernel.org/stable/c/3b097416b4cff77285c1f472fc2c4058d8a7554f"},{"url":"https://git.kernel.org/stable/c/df7d4d011d5ace20699ea948712f09f9ac08924f"},{"url":"https://git.kernel.org/stable/c/35d522bd32462afcf1981dab6da8a9256c26c1e0"}],"tags":["cve.org"],"epss":0.00164,"epssPercentile":0.06026,"ingestedAt":"2026-09-14T15:23:07.451Z","slug":"CVE-2026-89557","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= 2699b67223aca6b1450fc2f72e40fada952afc85 < 94c820d99a4305d4ded41a97ed37ec7d26c56e7f`\n- `Linux >= 2699b67223aca6b1450fc2f72e40fada952afc85 < 573fb68105fdc6a127ba6069e58a0d2aff3c9f93`\n- `Linux >= 2699b67223aca6b1450fc2f72e40fada952afc85 < 323f3a056dbccb39a642ebde642044a680f3a6d6`\n- `Linux >= 2699b67223aca6b1450fc2f72e40fada952afc85 < 0a03f9541c06fda64301dcf94f376f07ce2cc396`\n- `Linux >= 2699b67223aca6b1450fc2f72e40fada952afc85 < 75d15738fd33a782606d0dc80cfeff47edf2ddd8`\n- `Linux >= 2699b67223aca6b1450fc2f72e40fada952afc85 < 3b097416b4cff77285c1f472fc2c4058d8a7554f`\n- `Linux >= 2699b67223aca6b1450fc2f72e40fada952afc85 < df7d4d011d5ace20699ea948712f09f9ac08924f`\n- `Linux >= 2699b67223aca6b1450fc2f72e40fada952afc85 < 35d522bd32462afcf1981dab6da8a9256c26c1e0`\n- `Linux 3.1`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":197930,"id":"CVE-2026-89557","ts":1789384321006,"field":"cvss","old":"4.4","new":"7.8"},{"seq":197929,"id":"CVE-2026-89557","ts":1789384321006,"field":"severity","old":"medium","new":"high"},{"seq":183475,"id":"CVE-2026-89557","ts":1789356675518,"field":"cvss","old":"7.8","new":"4.4"},{"seq":183474,"id":"CVE-2026-89557","ts":1789356675518,"field":"severity","old":"high","new":"medium"},{"seq":153366,"id":"CVE-2026-89557","ts":1789285350227,"field":"cvss","old":null,"new":"7.8"},{"seq":153365,"id":"CVE-2026-89557","ts":1789285350227,"field":"severity","old":"none","new":"high"},{"seq":147718,"id":"CVE-2026-89557","ts":1789270212021,"field":"cvss","old":null,"new":"4.4"},{"seq":147717,"id":"CVE-2026-89557","ts":1789270212021,"field":"severity","old":"none","new":"medium"},{"seq":109468,"id":"CVE-2026-89557","ts":1789183732032,"field":"cvss","old":null,"new":"4.4"},{"seq":109467,"id":"CVE-2026-89557","ts":1789183732032,"field":"severity","old":"none","new":"medium"}]}