CVE-2023-53184

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

arm64/sme: Set new vector length before reallocating

As part of fixing the allocation of the buffer for SVE state when changing SME vector length we introduced an immediate reallocation of the SVE state, this is also done when changing the SVE vector length for consistency. Unfortunately this reallocation is done prior to writing the new vector length to the task struct, meaning the allocation is done with the old vector length and can lead to memory corruption due to an undersized buffer being used.

Move the update of the vector length before the allocation to ensure that the new vector length is taken into account.

For some reason this isn't triggering any problems when running tests on the arm64 fixes branch (even after repeated tries) but is triggering issues very often after merge into mainline.

This vulnerability is rated as Moderate. It stems from an incorrect ordering of state updates and memory allocation and primarily impacts availability, since it can lead to a kernel panic). The bug can also potentially have effects on confidentiality (though this would require precise control and is highly improbable), and integrity, since it could in theory overwrite adjacent kernel structures.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.