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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - GHES/AEPI kernel panic when a network device is detected (on rare PCIe hardware)"
href="https://bugs.freedesktop.org/show_bug.cgi?id=90262">90262</a>
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<th>Summary</th>
<td>GHES/AEPI kernel panic when a network device is detected (on rare PCIe hardware)
</td>
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<th>Product</th>
<td>systemd
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>x86-64 (AMD64)
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<th>OS</th>
<td>Linux (All)
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
</td>
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<th>Component</th>
<td>general
</td>
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<th>Assignee</th>
<td>systemd-bugs@lists.freedesktop.org
</td>
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<th>Reporter</th>
<td>jason.mcmullan@gmail.com
</td>
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<th>QA Contact</th>
<td>systemd-bugs@lists.freedesktop.org
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=115490" name="attach_115490" title="systemd-stable/v208 udev net_id PCIe config read patch">attachment 115490</a> <a href="attachment.cgi?id=115490&action=edit" title="systemd-stable/v208 udev net_id PCIe config read patch">[details]</a></span>
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().</pre>
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