UBUNTU-CVE-2026-97559: Low severity ubuntu/linux-hwe-edge vulnerability

In the Linux kernel, the following vulnerability has been resolved: smb: client: fail DACL rewrite when the new DACL exceeds 64K replacesidsandcopyaces() and setchmoddacl() accumulate the size of the DACL they build in a u16. That accumulator can wrap. validatedacl() caps numaces at (daclsize - sizeof(struct smbacl)) / 20, i.e. 3276 for a maximally sized DACL, while each rewritten ACE can grow to sizeof(struct smbace) (76 bytes) once its SID is replaced with one carrying SIDMAXSUBAUTHORITIES sub-authorities. The worst case is therefore sizeof(struct smbacl) + 3276 76 = 248984 bytes, far beyond what a u16 can hold. A wraparound is reached with 863 ACEs. After the wraparound, ndaclptr->size becomes meaningless and the offset will point anywhere in the ACE array. As a result, we will see corruption of the DACL, which then gets sent to the server. This is not an out-of-bounds write as the allocation now covers the worst-case expansion, so writes will always go into the buffer. Adjust the code to use a u32 internally and return -EOVERFLOW in the overflow case. The operation must be refused, because a DACL can only hold 2^16-1 bytes on the wire and larger DACLs cannot be represented. setchmoddacl() carries the same pattern and is fixed the same way. It only wraps once the source DACL comes within roughly 380 bytes of the 64K ceiling, but the failure mode is identical.