From: Michael Bommarito <michael.bommarito@gmail.com> stable inclusion from stable-v6.6.143 commit d3e9b79aa794f7a23e82de4d710e7d2df610e349 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/16216 CVE: CVE-2026-63888 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ 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 <michael.bommarito@gmail.com> Tested-by: John Garry <john.g.garry@oracle.com> Reviewed-by: John Garry <john.g.garry@oracle.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Lu Chentao <luchentao1@huawei.com> --- drivers/target/iscsi/iscsi_target.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c index b756d4cfecfe..5cad08685350 100644 --- a/drivers/target/iscsi/iscsi_target.c +++ b/drivers/target/iscsi/iscsi_target.c @@ -2333,12 +2333,13 @@ iscsit_handle_text_cmd(struct iscsit_conn *conn, struct iscsit_cmd *cmd, if (rx_got != rx_size) goto reject; if (conn->conn_ops->DataDigest) { iscsit_do_crypto_hash_buf(conn->conn_rx_hash, - text_in, rx_size, 0, NULL, - &data_crc); + text_in, + ALIGN(payload_length, 4), + 0, NULL, &data_crc); if (checksum != data_crc) { pr_err("Text data CRC32C DataDigest" " 0x%08x does not match computed" " 0x%08x\n", checksum, data_crc); @@ -2354,10 +2355,11 @@ iscsit_handle_text_cmd(struct iscsit_conn *conn, struct iscsit_cmd *cmd, */ pr_debug("Dropping Text" " Command CmdSN: 0x%08x due to" " DataCRC error.\n", hdr->cmdsn); kfree(text_in); + cmd->text_in_ptr = NULL; return 0; } } else { pr_debug("Got CRC32C DataDigest" " 0x%08x for %u bytes of text data.\n", -- 2.52.0