scsi: scsi_debug: Fix REPORT ZONES alloc_len underflow OOB write

Overview

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

• Linux >= ebacb44cb2042b90951140eda806bedad23ef554 < 7b615fc139e35c81077046df44725c532f7e2404
• Linux >= 7db0e0c8190a086ef92ce5bb960836cde49540aa < 5d3e1d006bbb543259f9e31824caadbfff6a5465
• Linux >= 7db0e0c8190a086ef92ce5bb960836cde49540aa < 49e5b25a0b74dbac595f122e5608fdce2918cc4e
• Linux >= 7db0e0c8190a086ef92ce5bb960836cde49540aa < 495058429ca55ab7fcc21977b63b92907ad68066
• Linux >= 7db0e0c8190a086ef92ce5bb960836cde49540aa < 2047ed09bf13453b7d6f9431b112ec07984dd69b
• Linux >= 7db0e0c8190a086ef92ce5bb960836cde49540aa < d6e6da6bc3b53231fac77ffab428da8173ee729c
• Linux >= 7db0e0c8190a086ef92ce5bb960836cde49540aa < 93dde0bf2f39a0f9f57fd610aa3201ce5b753433
• Linux c4d2d7c935a4ad20e8e726ca10499cefe4537103
• Linux >= 5.15.8 < 5.15.217
• Linux >= 5.10.85 < 5.11
• Linux 5.16

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.