High 7.8Published Sep 11, 2026

CVE-2026-89557md: do overflow check for sb->bblog_shift in super_1_load()

Updated under an hour ago (Oct 26, 2026, 1:00 PM ET)

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Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: md: do overflow check for sb->bblog_shift in super_1_load() In super_1_load(), sb->bblog_shift is an __u8 type value loaded from on- disk superblock. It is used for badblocks API badblocks_set() by the following sequence, 1930 rdev->badblocks.shift = sb->bblog_shift; 1931 for (i = 0 ; i < (sectors << (9-3)) ; i++, bbp++) { 1932 u64 bb = le64_to_cpu(*bbp); 1933 int count = bb & (0x3ff); 1934 u64 sector = bb >> 10; 1935 sector <<= sb->bblog_shift; 1936 count <<= sb->bblog_shift; 1937 if (bb + 1 == 0) 1938 break; 1939 if (!badblocks_set(&rdev->badblocks, sector, count, 1)) 1940 return -EINVAL; 1941 } bb->bblog_shit is in range of 0-255, variable sector is 64bit width, for an invalid bb->bblog_shit, it is possible to make sector be overflowed by the following calculation, 1935 sector <<= sb->bblog_shift; Then in turn when call badblocks_set() at line 1939 with the invalid rdev->badblocks.shift set at line 1930, may result an overflow inside _badblocks_clear() in block/badblocks.c. Although there are many places to call badblocks APIs, the non-zero shift value is only used in super_1_load(), other places always use 0 as the shift value. Therefore it is unnecessary to do a general shift value overflow check inside badblock API, and just check here as the caller. This may avoid unnecessary check, make the badblocks API code more simple and elegant.

CVSS: 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Received
Record last updated: Oct 19, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	2699b67223aca6b1450fc2f72e40fada952afc85 builds before 94c820d99a4305d4ded41a97ed37ec7d26c56e7f; 2699b67223aca6b1450fc2f72e40fada952afc85 builds before 573fb68105fdc6a127ba6069e58a0d2aff3c9f93; 2699b67223aca6b1450fc2f72e40fada952afc85 builds before 323f3a056dbccb39a642ebde642044a680f3a6d6; 2699b67223aca6b1450fc2f72e40fada952afc85 builds before 0a03f9541c06fda64301dcf94f376f07ce2cc396; 2699b67223aca6b1450fc2f72e40fada952afc85 builds before 75d15738fd33a782606d0dc80cfeff47edf2ddd8; 2699b67223aca6b1450fc2f72e40fada952afc85 builds before 3b097416b4cff77285c1f472fc2c4058d8a7554f; from 2699b67223aca6b1450fc2f72e40fada952afc85 before df7d4d011d5ace20699ea948712f09f9ac08924f; 2699b67223aca6b1450fc2f72e40fada952afc85 builds before 35d522bd32462afcf1981dab6da8a9256c26c1e0	CNA record

References

References

https://git.kernel.org/stable/c/94c820d99a4305d4ded41a97ed37ec7d26c56e7f
https://git.kernel.org/stable/c/573fb68105fdc6a127ba6069e58a0d2aff3c9f93
https://git.kernel.org/stable/c/323f3a056dbccb39a642ebde642044a680f3a6d6
https://git.kernel.org/stable/c/0a03f9541c06fda64301dcf94f376f07ce2cc396
https://git.kernel.org/stable/c/75d15738fd33a782606d0dc80cfeff47edf2ddd8
https://git.kernel.org/stable/c/3b097416b4cff77285c1f472fc2c4058d8a7554f
https://git.kernel.org/stable/c/df7d4d011d5ace20699ea948712f09f9ac08924f
https://git.kernel.org/stable/c/35d522bd32462afcf1981dab6da8a9256c26c1e0

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.