nvmet-tcp: fix page fragment cache leak in error path

Overview

In the Linux kernel, the following vulnerability has been resolved:

nvmet-tcp: fix page fragment cache leak in error path

In nvmet_tcp_alloc_queue(), when a connection is closed during the allocation process (e.g., nvmet_tcp_set_queue_sock() returns -ENOTCONN), the error handling jumps to out_destroy_sq and then to out_ida_remove without draining the page fragment cache.

Although nvmet_tcp_free_cmd() is called in some error paths to release individual page fragments, the underlying page cache reference held by queue->pf_cache is never released. The first allocation using pf_cache is the call to nvmet_tcp_alloc_cmd() for queue->connect, which happens after ida_alloc() returns successfully. This results in a page leak each time a connection fails during allocation, which could lead to memory exhaustion over time if connections are repeatedly opened and closed.

Fix this by calling page_frag_cache_drain() before freeing the queue structure in the out_ida_remove label.

Affected

• Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < fc11e3f0daaadb6e600a86e54b089d4662d0a464
• Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < a43a9abc1ebf663f0aa56a729106f68dd9c77da6
• Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < ba3209704b3cd46961e4e081af5c52a780785648
• Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < 5fbe83a374f09561a0f0c1f4aa021501ffd681eb
• Linux >= 872d26a391da92ed8f0c0f5cb5fef428067b7f30 < 4dae393956093c807212918fd91a8fc70df15338
• Linux 5.0

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.