CVE-2026-80710

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

s390/dasd: Fix undersized format-check buffer

fmt_buffer_size in dasd_eckd_check_device_format() is declared as

int, even though one of the multiplicands, sizeof(struct eckd_count),

is a size_t. The expression

trkcount * rpt_max * sizeof(struct eckd_count)

is therefore correctly evaluated at 64-bit width, but the result is

silently truncated when it is stored back into the 32-bit

fmt_buffer_size variable. For a sufficiently large track range

(start_unit/stop_unit are caller-controlled) this truncation

yields a buffer size far smaller than the number of tracks actually

requested. kzalloc() then succeeds with an undersized allocation,

while the subsequent channel program build still operates on the

untruncated track count and writes past the end of that buffer.

Compute the buffer size with check_mul_overflow() and keep it in a

size_t, so that a value that no longer fits results in -EINVAL

instead of a silently truncated allocation size.