CVE-2026-74470scsi: scsi_debug: Fix REPORT ZONES alloc_len underflow OOB write

Official description

In the Linux kernel, the following vulnerability has been resolved: scsi: scsi_debug: Fix REPORT ZONES alloc_len underflow OOB write resp_report_zones() sizes the reply buffer from the CDB allocation length. The v3 fix rounds alloc_len up with ALIGN() before deriving the descriptor count: rep_max_zones = (ALIGN((u64)alloc_len, RZONES_DESC_HD) - RZONES_DESC_HD) >> ilog2(RZONES_DESC_HD); arr_len = (u64)RZONES_DESC_HD * (rep_max_zones + 1); For alloc_len in 0xFFFFFFC1..0xFFFFFFFF, ALIGN() rounds up to 0x100000000, so arr_len is 4 GB. On 32-bit, kzalloc()'s size_t is 32-bit and truncates 0x100000000 to 0; kzalloc(0) returns ZERO_SIZE_PTR, which passes the !arr check, and desc = arr + 64 is then dereferenced in the loop -> out-of-bounds write / panic. Clamp rep_max_zones to devip->nr_zones. The loop already stops at sdebug_capacity (after nr_zones zones), so a report can never hold more than nr_zones descriptors; the clamp does not change the report, it only bounds arr_len to (nr_zones + 1) * RZONES_DESC_HD, a real device property that can never reach 0x100000000.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/7b615fc139e35c81077046df44725c532f7e2404
• https://git.kernel.org/stable/c/5d3e1d006bbb543259f9e31824caadbfff6a5465
• https://git.kernel.org/stable/c/49e5b25a0b74dbac595f122e5608fdce2918cc4e
• https://git.kernel.org/stable/c/495058429ca55ab7fcc21977b63b92907ad68066
• https://git.kernel.org/stable/c/2047ed09bf13453b7d6f9431b112ec07984dd69b
• https://git.kernel.org/stable/c/d6e6da6bc3b53231fac77ffab428da8173ee729c
• https://git.kernel.org/stable/c/93dde0bf2f39a0f9f57fd610aa3201ce5b753433