| Summary: | GHES/AEPI kernel panic when a network device is detected (on rare PCIe hardware) | ||
|---|---|---|---|
| Product: | systemd | Reporter: | Jason S. McMullan <jason.mcmullan> |
| Component: | general | Assignee: | Kay Sievers <kay> |
| Status: | RESOLVED FIXED | QA Contact: | systemd-bugs |
| Severity: | normal | ||
| Priority: | medium | ||
| Version: | unspecified | ||
| Hardware: | x86-64 (AMD64) | ||
| OS: | Linux (All) | ||
| Whiteboard: | |||
| i915 platform: | i915 features: | ||
| Attachments: |
systemd-stable/v208 udev net_id PCIe config read patch
systemd/master udev net_id PCIe config read patch |
||
Created attachment 115491 [details] [review] systemd/master udev net_id PCIe config read patch Kay, any idea when these patches can be integrated into the systemd mainline? Hi Jason, Thanks for the patch. I now pushed this upstream. Cheers, Tom |
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Created attachment 115490 [details] systemd-stable/v208 udev net_id PCIe config read patch Due to fread() buffering when fetching the PCIe config space, some rare PCIe hardware will generate a PCIe Completion Timeout when unknown PCIe config space values are read, causing a kernel panic on Dell r720/r730 and other systems which have AEPI/GHES reporting enabled in the Linux kernel and motherboard BIOS. The original code in src/udev/udev-builtin-net_id.c used fread(), which on some libc implementations (ie glibc 2.17) would pre-read a full 4K (PAGE_SIZE) of the PCI config space, when only 64 bytes were requested. I have recently come across PCIe hardware which responds with Completion Timeouts when accesses above 256 bytes are attempted. This can cause server systems - such as the Dell r720/r730 - that have GHES/AEPI support to cause an immediate kernel panic due to the failed PCI transaction. Attached are patches against systemd-stable/v208 (the version that I originally found the issue in) and systemd/master (head of line) which correct this issue by using read() instead of fread().