scsi: libiscsi: Initialize iscsi_conn->dd_data only if memory is allocated

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: scsi: libiscsi: Initialize iscsi_conn->dd_data only if memory is allocated In case of an ib_fast_reg_mr allocation failure during iSER setup, the machine hits a panic because iscsi_conn->dd_data is initialized unconditionally, even when no memory is allocated (dd_size == 0). This leads invalid pointer dereference during connection teardown. Fix by setting iscsi_conn->dd_data only if memory is actually allocated. Panic trace: ------------ iser: iser_create_fastreg_desc: Failed to allocate ib_fast_reg_mr err=-12 iser: iser_alloc_rx_descriptors: failed allocating rx descriptors / data buffers BUG: unable to handle page fault for address: fffffffffffffff8 RIP: 0010:swake_up_locked.part.5+0xa/0x40 Call Trace: complete+0x31/0x40 iscsi_iser_conn_stop+0x88/0xb0 [ib_iser] iscsi_stop_conn+0x66/0xc0 [scsi_transport_iscsi] iscsi_if_stop_conn+0x14a/0x150 [scsi_transport_iscsi] iscsi_if_rx+0x1135/0x1834 [scsi_transport_iscsi] ? netlink_lookup+0x12f/0x1b0 ? netlink_deliver_tap+0x2c/0x200 netlink_unicast+0x1ab/0x280 netlink_sendmsg+0x257/0x4f0 ? _copy_from_user+0x29/0x60 sock_sendmsg+0x5f/0x70

References

• https://git.kernel.org/stable/c/f53af99f441ee79599d8df6113a7144d74cf9153
• https://git.kernel.org/stable/c/9ea6d961566c7d762ed0204b06db05756fdda3b6
• https://git.kernel.org/stable/c/fd5aad080edb501ab5c84b7623d612d0e3033403
• https://git.kernel.org/stable/c/a145c269dc5380c063a20a0db7e6df2995962e9d
• https://git.kernel.org/stable/c/66a373f50b4249d57f5a88c7be9676f9d5884865
• https://git.kernel.org/stable/c/35782c32528d82aa21f84cb5ceb2abd3526a8159
• https://git.kernel.org/stable/c/a33d42b7fc24fe03f239fbb0880dd5b4b4b97c19
• https://git.kernel.org/stable/c/2b242ea14386a510010eabfbfc3ce81a101f3802
• https://git.kernel.org/stable/c/3ea3a256ed81f95ab0f3281a0e234b01a9cae605