scsi: target: core: Fix iSCSI ISID use-after-free in REGISTER AND MOVE

Overview

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

scsi: target: core: Fix iSCSI ISID use-after-free in REGISTER AND MOVE

core_scsi3_emulate_pro_register_and_move() maps the PERSISTENT RESERVE OUT parameter list with transport_kmap_data_sg() and parses the destination TransportID with target_parse_pr_out_transport_id(). For an iSCSI TransportID (FORMAT CODE 01b), iscsi_parse_pr_out_transport_id() returns the ISID in iport_ptr as a raw pointer into that mapped buffer.

The function then unmaps the buffer with transport_kunmap_data_sg() before dereferencing iport_ptr in strcmp(), __core_scsi3_locate_pr_reg() and core_scsi3_alloc_registration(). When the parameter list spans more than one page (PARAMETER LIST LENGTH > 4096), transport_kmap_data_sg() uses vmap() and transport_kunmap_data_sg() does vunmap(), so the kernel virtual address backing iport_ptr is torn down and every subsequent dereference is a use-after-free read of the unmapped region.

Keep the parameter list mapped until iport_ptr is no longer needed: drop the early transport_kunmap_data_sg() and unmap once on the success path, right before returning. The error paths already unmap through the existing "if (buf) transport_kunmap_data_sg(cmd)" at the out: label, which now runs on every post-map error exit because buf is no longer cleared early. Only reads of the mapping happen while spinlocks are held; the map and unmap calls remain outside any lock. The sibling caller core_scsi3_decode_spec_i_port() already uses the buffer before unmapping it and is left unchanged.

Affected

• Linux >= 4949314c7283ea4f9ade182ca599583b89f7edd6 < 7d56f5c868d92c9d504a34a3ea450bce481c7f63
• Linux >= 4949314c7283ea4f9ade182ca599583b89f7edd6 < 59a2a5a37dc49a641ad6bc64aee34e5a61025ffd
• Linux >= 4949314c7283ea4f9ade182ca599583b89f7edd6 < 9f8076cc73dfa6b10155978c160587e986b22169
• Linux >= 4949314c7283ea4f9ade182ca599583b89f7edd6 < a040004846f1fbe687f6ec76d9ccc27b4ead42e4
• Linux >= 4949314c7283ea4f9ade182ca599583b89f7edd6 < 05b3e37433cf2eaf8867f1c16528aa347bb212ab
• Linux >= 4949314c7283ea4f9ade182ca599583b89f7edd6 < cb7bdae7fba404852ade34b0c1445fbaf3e54fbb
• Linux >= 4949314c7283ea4f9ade182ca599583b89f7edd6 < ef2ee18fec92088c7d8877baf7674e89389ccd66
• Linux >= 4949314c7283ea4f9ade182ca599583b89f7edd6 < fda6a1f3c3d7047b5ce5654487649c2daa738bfc
• Linux d2227f84ba0e97906153ac83db13213fb2e3938d
• Linux >= 3.2.9 < 3.3
• Linux 3.3

Remediation

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