diff options
| author | Colin Percival <cperciva@FreeBSD.org> | 2026-03-14 05:51:04 +0000 |
|---|---|---|
| committer | Colin Percival <cperciva@FreeBSD.org> | 2026-03-28 05:53:42 +0000 |
| commit | 5809c9a77b2d3b83c056ba3ac5ba4e261c0af595 (patch) | |
| tree | 4bbdd8b5632fbda4dea39970bc5b7437f3d1f08d | |
| parent | 1d0ccd61563d48e914dccf3dd5cf0280d8331ec1 (diff) | |
io_apic: Don't route to APIC ID > 255
I/O APIC Redirection Table Entries use 8 bits to encode the Destination
ID. Attempting to route an IRQ to a higher APIC ID would result in it
being silently routed to the value reduced modulo 256, causing a panic
if the IRQ fired since the receiving CPU would not expect that IRQ.
Instead, print a warning and mark the interrupt as invalid, resulting
in it being forcibly masked.
Reviewed by: kib
Tested on: EC2 r8i.96xlarge
MFC after: 3 weeks
Sponsored by: Amazon
Differential Revision: https://reviews.freebsd.org/D55857
| -rw-r--r-- | sys/x86/x86/io_apic.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/sys/x86/x86/io_apic.c b/sys/x86/x86/io_apic.c index 03d85acabb1a..5d28b7e8c611 100644 --- a/sys/x86/x86/io_apic.c +++ b/sys/x86/x86/io_apic.c @@ -364,10 +364,20 @@ ioapic_program_intpin(struct ioapic_intsrc *intpin) /* * Set the destination. Note that with Intel interrupt remapping, * the previously reserved bits 55:48 now have a purpose so ensure - * these are zero. + * these are zero. If the CPU number (in fact, APIC ID) is too + * large, mark the interrupt as invalid, and target CPU #0. */ - low = IOART_DESTPHY; - high = intpin->io_cpu << APIC_ID_SHIFT; + if (intpin->io_cpu <= IOAPIC_MAX_ID) { + low = IOART_DESTPHY; + high = intpin->io_cpu << APIC_ID_SHIFT; + intpin->io_valid = 1; + } else { + printf("%s: unsupported destination APIC ID %u for pin %u\n", + __func__, intpin->io_cpu, intpin->io_intpin); + low = IOART_DESTPHY; + high = 0 << APIC_ID_SHIFT; + intpin->io_valid = 0; + } /* Program the rest of the low word. */ if (intpin->io_edgetrigger) |