CVE-2026-89557

Status: UPDATED  |  Advisory ID: CVE-2026-89557

Key Details

Affected Products, Subsystems & Sectors

What to Know

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. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References