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CVE-2026-89557

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

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109, and 2 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: total

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: total

  3. Record last updated

Affected versions

  • Linux Linux

    From 2699b67223aca6b1450fc2f72e40fada952afc85 · fixed in 94c820d99a4305d4ded41a97ed37ec7d26c56e7f; From 2699b67223aca6b1450fc2f72e40fada952afc85 · fixed in 573fb68105fdc6a127ba6069e58a0d2aff3c9f93; From 2699b67223aca6b1450fc2f72e40fada952afc85 · fixed in 323f3a056dbccb39a642ebde642044a680f3a6d6; From 2699b67223aca6b1450fc2f72e40fada952afc85 · fixed in 0a03f9541c06fda64301dcf94f376f07ce2cc396; From 2699b67223aca6b1450fc2f72e40fada952afc85 · fixed in 75d15738fd33a782606d0dc80cfeff47edf2ddd8; From 2699b67223aca6b1450fc2f72e40fada952afc85 · fixed in 3b097416b4cff77285c1f472fc2c4058d8a7554f; From 2699b67223aca6b1450fc2f72e40fada952afc85 · fixed in df7d4d011d5ace20699ea948712f09f9ac08924f; From 2699b67223aca6b1450fc2f72e40fada952afc85 · fixed in 35d522bd32462afcf1981dab6da8a9256c26c1e0

  • Linux Linux

    3.1

  • KernelLinux

    From 3.1.0 · fixed in 5.10.270; From 5.11.0 · fixed in 5.15.221; From 5.16.0 · fixed in 6.1.188; From 6.2.0 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.109; From 6.13.0 · fixed in 6.18.50; From 6.19.0 · fixed in 7.2.4

References 8

git.kernel.org