kernel/git/stable/linux.git/drivers/target/iscsi, branch master

scsi: target: iscsi: Reserve a terminator byte for the login payload

2026-09-02T02:08:31+00:00

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. Fixes: e48354ce078c ("iscsi-target: Add iSCSI fabric support for target v4.1") Assisted-by: Claude Opus5 (custom harness) Cc: stable@vger.kernel.org Signed-off-by: Sujal Tuladhar Signed-off-by: Martin K. Petersen (Oracle)

scsi: target: iscsi: Fix hang for aborted WRITE_PENDING commands

2026-08-29T02:18:58+00:00

When a LUN_RESET aborts a WRITE command that is in the TRANSPORT_WRITE_PENDING state, the target core sets CMD_T_ABORTED and waits for the frontend to finish processing. If the initiator subsequently sends the remaining dataout PDUs, __iscsit_check_dataout_hdr() catches the payload, stops the dataout timer if the sequence is final and finally dumps the data. However, the iSCSI target doesn't trigger the completion process for these aborted commands. Because of this, the abort path hangs indefinitely in target_put_cmd_and_wait(), leading to a deadlocked target worker thread. Fix this by explicitly calling target_complete_cmd() when the final dataout PDU is received for an aborted WRITE command. target_complete_cmd() detects the CMD_T_ABORTED flag and cleanly routes the command into target_abort_work, allowing the abort completion to successfully unblock. Signed-off-by: Maurizio Lombardi Reviewed-by: Laurence Oberman Link: https://patch.msgid.link/20260717143828.76291-2-mlombard@redhat.com Signed-off-by: Martin K. Petersen (Oracle)

scsi: target: Use constant-time crypto_memneq() for CHAP digests

2026-06-08T21:20:33+00:00

A constant-time memory comparison is more suitable than plain memcmp() for authentication digest comparison. CHAP digests use an authenticator-provided random challenge, so any timing side-channel shouldn't be easily exploitable. Reported-by: Sashiko (gemini/gemini-3.1-pro-preview) Link: https://sashiko.dev/#/patchset/20260521151121.808477-1-hossu.alexandru%40gmail.com Signed-off-by: David Disseldorp Reviewed-by: Lee Duncan Link: https://patch.msgid.link/20260605122019.24146-3-ddiss@suse.de Signed-off-by: Martin K. Petersen

scsi: target: Fix hexadecimal CHAP_I handling

2026-06-08T21:20:33+00:00

A mutual CHAP handshake requires target processing of an initiator-sent CHAP_I identifier. The RFC 3720 specification states: 11.1.4. Challenge Handshake Authentication Protocol (CHAP) ... CHAP_A= CHAP_I= CHAP_C= ... Where N, (A,A1,A2), I, C, and R are (correspondingly) the Name, Algorithm, Identifier, Challenge, and Response as defined in [RFC1994], N is a text string, A,A1,A2, and I are numbers CHAP_I parsing currently calls extract_param(), which returns the @identifier string (stripped of any 0b/0B or 0x/0X prefix) and a @type which indicates DECIMAL, HEX, or BASE64 encoding (based on any stripped prefix). Any HEX encoded CHAP_I string is further processed via: ret = kstrtoul(&identifier[2], 0, &id); This is incorrect for two reasons: * The @identifier string has already been stripped of the 0x/0X prefix, so skipping the first two bytes omits part of the number. * The kstrtoul() call specifies a base of 0, which will see &identifier[2] parsed as a decimal, unless a '0x' or (octal) '0' is erroneously present at that offset. Fix this by passing the (zero-offset) identifier string to kstrtoul() along with a base=16 parameter. Also add an explicit error handler for BASE64 encoding. Hex-encoded CHAP_I handling can be testing using the libiscsi EncodedI test linked below. Reported-by: Sashiko (gemini/gemini-3.1-pro-preview) Link: https://sashiko.dev/#/patchset/20260521151121.808477-1-hossu.alexandru%40gmail.com Link: https://github.com/sahlberg/libiscsi/pull/473 Fixes: 85db7391310b ("scsi: target: iscsi: Validate CHAP_R length before base64 decode") Signed-off-by: David Disseldorp Reviewed-by: Lee Duncan Reviewed-by: John Garry Link: https://patch.msgid.link/20260605122019.24146-2-ddiss@suse.de Signed-off-by: Martin K. Petersen

scsi: target: iscsi: Validate CHAP_R length before base64 decode

2026-05-23T03:06:00+00:00
chap_server_compute_hash() allocates client_digest as kzalloc(chap->digest_size) and then, for BASE64-encoded responses, passes chap_r directly to chap_base64_decode() without checking whether the input length could produce more than digest_size bytes of output. chap_base64_decode() writes to the destination unconditionally as long as there is input to consume. With MAX_RESPONSE_LENGTH set to 128 and the "0b" prefix stripped by extract_param(), up to 127 base64 characters can reach the decoder. 127 characters decode to 95 bytes. For SHA-256 (digest_size=32) this overflows client_digest by 63 bytes; for MD5 (digest_size=16) the overflow is 79 bytes. The length check at line 344 fires after the write has already happened. The HEX branch in the same switch statement already validates the length up front. Apply the same approach to the BASE64 branch: strip trailing base64 padding characters, then reject any input whose data length exceeds DIV_ROUND_UP(digest_size * 4, 3) before calling the decoder. Stripping trailing '=' before the comparison handles both padded and unpadded encodings. chap_base64_decode() already returns early on '=', so the full original string is still passed to the decoder unchanged. The mutual CHAP path decodes CHAP_C into initiatorchg_binhex, which is kzalloc(CHAP_CHALLENGE_STR_LEN). extract_param() caps initiatorchg at CHAP_CHALLENGE_STR_LEN characters, so at most CHAP_CHALLENGE_STR_LEN-1 base64 characters reach the decoder. The maximum decoded size, DIV_ROUND_UP((CHAP_CHALLENGE_STR_LEN-1) * 3, 4), is less than CHAP_CHALLENGE_STR_LEN, so no overflow is possible there. A comment is added at the call site to document this. Fixes: 1e5733883421 ("scsi: target: iscsi: Support base64 in CHAP") Cc: stable@vger.kernel.org Signed-off-by: Alexandru Hossu Reviewed-by: David Disseldorp Link: https://patch.msgid.link/20260521151121.808477-1-hossu.alexandru@gmail.com Signed-off-by: Martin K. Petersen

scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf

2026-05-23T03:04:36+00:00
iscsi_encode_text_output() concatenates "key=value\0" records into login->rsp_buf, an 8192-byte kzalloc(MAX_KEY_VALUE_PAIRS) buffer allocated in iscsit_alloc_login_setup_buffer(). The three sprintf() call sites in this function (lines 1398, 1411, 1424 in v7.1-rc2) never check the remaining buffer capacity: *length += sprintf(output_buf, "%s=%s", er->key, er->value); *length += 1; output_buf = textbuf + *length; The 8192-byte ceiling at iscsi_target_check_login_request() bounds the *input* Login PDU payload, but a single PDU can carry up to 2048 minimal four-byte "a=b\0" pairs, each unknown key expanding to a 16-byte "a=NotUnderstood\0" output record via iscsi_add_notunderstood_response(). 2048 * 16 = 32 KiB of output into an 8 KiB buffer, producing a ~24 KiB heap overrun in the kmalloc-8k slab. The fix introduces a static iscsi_encode_text_record() helper that uses snprintf() with a per-call bounds check against the remaining buffer, and threads a u32 textbuf_size parameter through iscsi_encode_text_output(). Both call sites in iscsi_target_handle_csg_zero() (PHASE_SECURITY) and iscsi_target_handle_csg_one() (PHASE_OPERATIONAL) pass MAX_KEY_VALUE_PAIRS. On overflow the encoder logs the condition, calls iscsi_release_extra_responses() to drop queued records, and returns -1; both caller sites now emit ISCSI_STATUS_CLS_INITIATOR_ERR / ISCSI_LOGIN_STATUS_INIT_ERR via iscsit_tx_login_rsp() before returning, so the initiator sees an explicit failed-login response rather than a silent connection drop. (Prior to this patch only the PHASE_OPERATIONAL caller did that; the PHASE_SECURITY caller is converted to the same shape.) Fixes: e48354ce078c ("iscsi-target: Add iSCSI fabric support for target v4.1") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Michael Bommarito Tested-by: John Garry Reviewed-by: John Garry Signed-off-by: Martin K. Petersen

scsi: target: iscsi: Fix CRC overread and double-free in iscsit_handle_text_cmd()

2026-05-23T02:24:16+00:00
Two latent bugs in the Text-phase handler, both present since the original LIO integration in commit e48354ce078c ("iscsi-target: Add iSCSI fabric support for target v4.1"): 1) DataDigest CRC buffer overread (4 bytes past text_in). text_in is kzalloc()'d at ALIGN(payload_length, 4). rx_size is then incremented by ISCSI_CRC_LEN to make room for the received DataDigest in the iovec, but the same (now-bumped) rx_size is passed as the buffer length to iscsit_crc_buf(): if (conn->conn_ops->DataDigest) { ... rx_size += ISCSI_CRC_LEN; } ... if (conn->conn_ops->DataDigest) { data_crc = iscsit_crc_buf(text_in, rx_size, 0, NULL); iscsit_crc_buf() walks rx_size bytes of text_in with crc32c(), so when DataDigest is negotiated it reads 4 bytes past the end of the text_in allocation. KASAN reproduces this directly on the unpatched mainline tree as slab-out-of-bounds in crc32c() called from the Text PDU path. The OOB bytes feed crc32c() and are then compared against the initiator-supplied checksum, so the value does not flow back to the attacker, but the kernel does read past the buffer on every Text PDU with DataDigest=CRC32C. Fix by passing the actual padded payload length (ALIGN(payload_length, 4)) that was used for the kzalloc(). 2) Stale cmd->text_in_ptr re-free (double-free) on ERL>0 bad DataDigest drop. On DataDigest mismatch with ErrorRecoveryLevel > 0 the handler silently drops the PDU and lets the initiator plug the CmdSN gap: kfree(text_in); return 0; cmd->text_in_ptr still points at the freed buffer. The next Text Request on the same ITT re-enters iscsit_setup_text_cmd(), which unconditionally does kfree(cmd->text_in_ptr); cmd->text_in_ptr = NULL; freeing the same pointer a second time. Session teardown via iscsit_release_cmd() has the same shape and hits the same double-free if the connection is dropped before a second Text Request arrives. On an unmodified mainline tree the bug-1 CRC overread fires first on the initial valid Text Request and perturbs the subsequent state, so #4 was isolated by building a kernel with only the bug-1 hunk of this patch applied plus temporary printk() observability around the three relevant kfree() sites. The observability prints are not part of this patch. On that build, a three-PDU Text Request sequence after login produces two back-to-back splats: BUG: KASAN: double-free in iscsit_setup_text_cmd+0x?? BUG: KASAN: double-free in iscsit_release_cmd+0x?? showing the same pointer freed in the ERL>0 drop path and again in iscsit_setup_text_cmd() (next Text Request on the same ITT) and once more in iscsit_release_cmd() (session teardown). On distro kernels with CONFIG_SLAB_FREELIST_HARDENED=y (default) the double-free becomes a remote kernel BUG(); on non-hardened kernels it corrupts the slab freelist. Fix by clearing cmd->text_in_ptr after the kfree() in the ERL>0 drop path. With both hunks applied #4 is directly observable on the stock tree without observability printks; fixing bug-1 alone would mask #4 less, not more, so the hunks are submitted together. Both fixes are one-liners. The Text PDU state machine is unchanged and the wire protocol is unaffected. Fixes: e48354ce078c ("iscsi-target: Add iSCSI fabric support for target v4.1") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Michael Bommarito Tested-by: John Garry Reviewed-by: John Garry Signed-off-by: Martin K. Petersen

scsi: target: iscsi: reject invalid size Extended CDB AHS

2026-04-22T01:08:25+00:00
If ecdb_ahdr->ahslength is zero, two bugs follow: kmalloc(be16_to_cpu(ecdb_ahdr->ahslength) + 15, ...) allocates 15 bytes, but the immediately following memcpy writes ISCSI_CDB_SIZE (16) bytes into it, a one-byte heap overflow. Also: memcpy(cdb + ISCSI_CDB_SIZE, ecdb_ahdr->ecdb, be16_to_cpu(ecdb_ahdr->ahslength) - 1); (u16)0 - 1 promotes to (int)-1 which converts to SIZE_MAX as size_t, causing a massive out-of-bounds write. Reject ahslength == 0 with ISCSI_REASON_PROTOCOL_ERROR before the kmalloc. Also reject ahslength values that exceed the actual AHS buffer advertised. Fixes: 8f1f7d297bce ("scsi: target: iscsi: Add support for extended CDB AHS") Signed-off-by: Carlos Bilbao Reviewed-by: Dmitry Bogdanov Link: https://patch.msgid.link/20260415040728.187680-1-carlos.bilbao@kernel.org Signed-off-by: Martin K. Petersen

scsi: target: Use driver completion preference by default

2026-03-01T02:04:02+00:00
This has us use the driver's completion preference by default. There is no behavior changes with this patch and we queue completion to LIO's completion workqueue by default. Signed-off-by: Mike Christie Link: https://patch.msgid.link/20260222232946.7637-3-michael.christie@oracle.com Signed-off-by: Martin K. Petersen

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00
This was done entirely with mindless brute force, using git grep -l '\