CVE-2026-90011scsi: target: iscsi: Reserve a terminator byte for the login payload

Official description

In the Linux kernel, the following vulnerability has been resolved: scsi: target: iscsi: Reserve a terminator byte for the login payload iscsi_target_check_login_request() rejects a login PDU whose DataSegmentLength exceeds MAX_KEY_VALUE_PAIRS, but the test is '>' and login->req_buf is allocated with exactly MAX_KEY_VALUE_PAIRS bytes. Since iscsit_get_login_rx() receives payload_length + padding bytes, where padding = ((-payload_length) & 3); any payload_length from 8189 to 8192 fills the whole 8192 byte buffer. The write stays in bounds, but no byte is left for a NUL terminator. The buffer is subsequently consumed as a C string. In the CHAP path chap_check_algorithm() calls kstrdup(a_str), and extract_param() calls strstr(in_buf, pattern) followed by strlen_semi(), none of which take a length. convert_null_to_semi() additionally rewrites every embedded NUL to ';', so even a payload made of well formed NUL separated key=value records is left without a terminator. These walk past the end of the object into adjacent slab memory. It is reachable by an unauthenticated initiator against a portal configured for CHAP; when authentication is not required iscsi_login_zero_tsih_s2() rewrites AuthMethod to None and the CHAP path is never entered. Allocate one extra byte. kzalloc() zeroes it and nothing ever writes to it, as every writer copies to offset 0 for at most MAX_KEY_VALUE_PAIRS bytes, so the buffer is always terminated.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/5fac79f248c37774d1dd761406f83d25ca6ff8e4
• https://git.kernel.org/stable/c/6ddddcad436d8e6e619204d3c848147ff2f5bf1e
• https://git.kernel.org/stable/c/b19dc17ed963ac36c0db4b52a1803fb11169f91f
• https://git.kernel.org/stable/c/6b589ef9d5f6cdc70d2b4f269ca6cf26b5ebb076
• https://git.kernel.org/stable/c/eb9dadf4d552ebe10644871c5189286552aa48f5
• https://git.kernel.org/stable/c/1624bff4c5118ad494d50ad94d44f22064667a7f
• https://git.kernel.org/stable/c/3ddf3ea291a0ef2ea93b82e158960ac2cc42302b
• https://git.kernel.org/stable/c/f4825922d2fb371e2b969697d792077f1b62b62c