CVE-2023-53509

/// Technical description

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

qed: allow sleep in qed_mcp_trace_dump()

By default, qed_mcp_cmd_and_union() delays 10us at a time in a loop

that can run 500K times, so calls to qed_mcp_nvm_rd_cmd()

may block the current thread for over 5s.

We observed thread scheduling delays over 700ms in production,

with stacktraces pointing to this code as the culprit.

qed_mcp_trace_dump() is called from ethtool, so sleeping is permitted.

It already can sleep in qed_mcp_halt(), which calls qed_mcp_cmd().

Add a "can sleep" parameter to qed_find_nvram_image() and

qed_nvram_read() so they can sleep during qed_mcp_trace_dump().

qed_mcp_trace_get_meta_info() and qed_mcp_trace_read_meta(),

called only by qed_mcp_trace_dump(), allow these functions to sleep.

I can't tell if the other caller (qed_grc_dump_mcp_hw_dump()) can sleep,

so keep b_can_sleep set to false when it calls these functions.

An example stacktrace from a custom warning we added to the kernel

showing

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References