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.