kernel/linux.git/drivers/target/iscsi, branch v6.1.176

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

2026-06-19T11:37:29+00:00

[ Upstream commit 778c2ab142c625a8a8afa570e0f9b7873f445d99 ] 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 Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

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

2026-06-19T11:37:05+00:00

commit 85db7391310b1304d2dc8ae3b0b12105a9567147 upstream. 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 Signed-off-by: Greg Kroah-Hartman

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

2026-06-19T11:37:05+00:00

commit bf33e01f88388c43e285492a63e539df6ffed64c upstream. 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 Signed-off-by: Greg Kroah-Hartman

scsi: target: iscsi: Fix use-after-free in iscsit_dec_conn_usage_count()

2026-02-11T12:37:24+00:00

[ Upstream commit 9411a89e9e7135cc459178fa77a3f1d6191ae903 ] In iscsit_dec_conn_usage_count(), the function calls complete() while holding the conn->conn_usage_lock. As soon as complete() is invoked, the waiter (such as iscsit_close_connection()) may wake up and proceed to free the iscsit_conn structure. If the waiter frees the memory before the current thread reaches spin_unlock_bh(), it results in a KASAN slab-use-after-free as the function attempts to release a lock within the already-freed connection structure. Fix this by releasing the spinlock before calling complete(). Signed-off-by: Maurizio Lombardi Reported-by: Zhaojuan Guo Reviewed-by: Mike Christie Link: https://patch.msgid.link/20260112165352.138606-2-mlombard@redhat.com Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin

scsi: target: iscsi: Fix use-after-free in iscsit_dec_session_usage_count()

2026-02-11T12:37:24+00:00

[ Upstream commit 84dc6037390b8607c5551047d3970336cb51ba9a ] In iscsit_dec_session_usage_count(), the function calls complete() while holding the sess->session_usage_lock. Similar to the connection usage count logic, the waiter signaled by complete() (e.g., in the session release path) may wake up and free the iscsit_session structure immediately. This creates a race condition where the current thread may attempt to execute spin_unlock_bh() on a session structure that has already been deallocated, resulting in a KASAN slab-use-after-free. To resolve this, release the session_usage_lock before calling complete() to ensure all dereferences of the sess pointer are finished before the waiter is allowed to proceed with deallocation. Signed-off-by: Maurizio Lombardi Reported-by: Zhaojuan Guo Reviewed-by: Mike Christie Link: https://patch.msgid.link/20260112165352.138606-3-mlombard@redhat.com Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin

scsi: target: iscsi: Fix timeout on deleted connection

2025-06-04T12:40:01+00:00

[ Upstream commit 7f533cc5ee4c4436cee51dc58e81dfd9c3384418 ] NOPIN response timer may expire on a deleted connection and crash with such logs: Did not receive response to NOPIN on CID: 0, failing connection for I_T Nexus (null),i,0x00023d000125,iqn.2017-01.com.iscsi.target,t,0x3d BUG: Kernel NULL pointer dereference on read at 0x00000000 NIP strlcpy+0x8/0xb0 LR iscsit_fill_cxn_timeout_err_stats+0x5c/0xc0 [iscsi_target_mod] Call Trace: iscsit_handle_nopin_response_timeout+0xfc/0x120 [iscsi_target_mod] call_timer_fn+0x58/0x1f0 run_timer_softirq+0x740/0x860 __do_softirq+0x16c/0x420 irq_exit+0x188/0x1c0 timer_interrupt+0x184/0x410 That is because nopin response timer may be re-started on nopin timer expiration. Stop nopin timer before stopping the nopin response timer to be sure that no one of them will be re-started. Signed-off-by: Dmitry Bogdanov Link: https://lore.kernel.org/r/20241224101757.32300-1-d.bogdanov@yadro.com Reviewed-by: Maurizio Lombardi Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin

scsi: target: iscsi: Fix buffer overflow in lio_target_nacl_info_show()

2023-09-23T09:11:07+00:00

[ Upstream commit 801f287c93ff95582b0a2d2163f12870a2f076d4 ] The function lio_target_nacl_info_show() uses sprintf() in a loop to print details for every iSCSI connection in a session without checking for the buffer length. With enough iSCSI connections it's possible to overflow the buffer provided by configfs and corrupt the memory. This patch replaces sprintf() with sysfs_emit_at() that checks for buffer boundries. Signed-off-by: Konstantin Shelekhin Link: https://lore.kernel.org/r/20230722152657.168859-2-k.shelekhin@yadro.com Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin

scsi: target: iscsi: Prevent login threads from racing between each other

2023-06-28T09:12:35+00:00

[ Upstream commit 2a737d3b8c792400118d6cf94958f559de9c5e59 ] The tpg->np_login_sem is a semaphore that is used to serialize the login process when multiple login threads run concurrently against the same target portal group. The iscsi_target_locate_portal() function finds the tpg, calls iscsit_access_np() against the np_login_sem semaphore and saves the tpg pointer in conn->tpg; If iscsi_target_locate_portal() fails, the caller will check for the conn->tpg pointer and, if it's not NULL, then it will assume that iscsi_target_locate_portal() called iscsit_access_np() on the semaphore. Make sure that conn->tpg gets initialized only if iscsit_access_np() was successful, otherwise iscsit_deaccess_np() may end up being called against a semaphore we never took, allowing more than one thread to access the same tpg. Signed-off-by: Maurizio Lombardi Link: https://lore.kernel.org/r/20230508162219.1731964-4-mlombard@redhat.com Reviewed-by: Mike Christie Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin

scsi: target: iscsit: Free cmds before session free

2023-05-24T16:32:37+00:00

[ Upstream commit d8990b5a4d065f38f35d69bcd627ec5a7f8330ca ] Commands from recovery entries are freed after session has been closed. That leads to use-after-free at command free or NPE with such call trace: Time2Retain timer expired for SID: 1, cleaning up iSCSI session. BUG: kernel NULL pointer dereference, address: 0000000000000140 RIP: 0010:sbitmap_queue_clear+0x3a/0xa0 Call Trace: target_release_cmd_kref+0xd1/0x1f0 [target_core_mod] transport_generic_free_cmd+0xd1/0x180 [target_core_mod] iscsit_free_cmd+0x53/0xd0 [iscsi_target_mod] iscsit_free_connection_recovery_entries+0x29d/0x320 [iscsi_target_mod] iscsit_close_session+0x13a/0x140 [iscsi_target_mod] iscsit_check_post_dataout+0x440/0x440 [iscsi_target_mod] call_timer_fn+0x24/0x140 Move cleanup of recovery enrties to before session freeing. Reported-by: Forza Signed-off-by: Dmitry Bogdanov Signed-off-by: Mike Christie Link: https://lore.kernel.org/r/20230319015620.96006-7-michael.christie@oracle.com Reviewed-by: Maurizio Lombardi Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin

scsi: target: iscsit: Fix TAS handling during conn cleanup

2023-05-11T14:03:19+00:00

[ Upstream commit cc79da306ebb2edb700c3816b90219223182ac3c ] Fix a bug added in commit f36199355c64 ("scsi: target: iscsi: Fix cmd abort fabric stop race"). If CMD_T_TAS is set on the se_cmd we must call iscsit_free_cmd() to do the last put on the cmd and free it, because the connection is down and we will not up sending the response and doing the put from the normal I/O path. Add a check for CMD_T_TAS in iscsit_release_commands_from_conn() so we now detect this case and run iscsit_free_cmd(). Fixes: f36199355c64 ("scsi: target: iscsi: Fix cmd abort fabric stop race") Signed-off-by: Mike Christie Link: https://lore.kernel.org/r/20230319015620.96006-9-michael.christie@oracle.com Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin