CVE-2026-53059

In the Linux kernel, the following vulnerability has been resolved:

dm log: fix out-of-bounds write due to region_count overflow

The local variable region_count in create_log_context() is declared as unsigned int (32-bit), but dm_sector_div_up() returns sector_t (64-bit). When a device-mapper target has a sufficiently large ti->len with a small region_size, the division result can exceed UINT_MAX. The truncated value is then used to calculate bitset_size, causing clean_bits, sync_bits, and recovering_bits to be allocated far smaller than needed for the actual number of regions.

Subsequent log operations (log_set_bit, log_clear_bit, log_test_bit) use region indices derived from the full untruncated region space, causing out-of-bounds writes to kernel heap memory allocated by vmalloc.

This can be reproduced by creating a mirror target whose region_count overflows 32 bits:

dmsetup create bigzero –table 0 8589934594 zero dmsetup create mymirror –table 0 8589934594 mirror core 2 2 nosync 2 /dev/mapper/bigzero 0 /dev/mapper/bigzero 0

The status output confirms the truncation (sync_count=1 instead of 4294967297, because 0x100000001 was truncated to 1):

$ dmsetup status mymirror 0 8589934594 mirror 2 254:1 254:1 1/4294967297 …

This leads to a kernel crash in core_in_sync:

BUG: scheduling while atomic: (udev-worker)/9150/0x00000000 RIP: 0010:core_in_sync+0x14/0x30 [dm_log] CR2: 0000000000000008 Fixing recursive fault but reboot is needed!

Fix by widening the local region_count to sector_t and adding an explicit overflow check before the value is assigned to lc->region_count.

Weakness

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

Affected Software

Potential Mitigations

• Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
• If possible, choose a language or compiler that performs automatic bounds checking.
• Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
• Use libraries or frameworks that make it easier to handle numbers without unexpected consequences.
• Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++). [REF-106]
• Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range.
• Use unsigned integers where possible. This makes it easier to perform validation for integer overflows. When signed integers are required, ensure that the range check includes minimum values as well as maximum values.
• Understand the programming language’s underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, “not-a-number” calculations, and how the language handles numbers that are too large or too small for its underlying representation. [REF-7]
• Also be careful to account for 32-bit, 64-bit, and other potential differences that may affect the numeric representation.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/92.html

References

• https://git.kernel.org/stable/c/12bd5b88e91a02785244ff1d20fb157e96e9cdc8
• https://git.kernel.org/stable/c/3ec74da927b4e171a6fc0e77b1188ba4d019af51
• https://git.kernel.org/stable/c/44ab8875ae4a2842bde2d756bed195d375e0debb
• https://git.kernel.org/stable/c/4ec8323b9f0764a14d532b1ae9b87f8a9fecb867
• https://git.kernel.org/stable/c/b455903eed4558982be0811f5b7f44f6bbc4ff57
• https://git.kernel.org/stable/c/c20e36b7631d83e7535877f08af8b0af72c44b1a
• https://git.kernel.org/stable/c/d4ac87567f86a55c3c92e9a5144dcd943a9772a1
• https://git.kernel.org/stable/c/defe483e47173768c227532694dc78cb65db5f09
• https://access.redhat.com/security/cve/CVE-2026-53059
• https://bugzilla.redhat.com/show_bug.cgi?id=2492277
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53059.json