haraldwolff/qemu-patch-raspberry4
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qxl: map rom r/o

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Map qxl rom read-only into the guest, so the guest can't tamper with the
content.  qxl has a shadow copy of the rom to deal with that, but the
shadow doesn't cover the mode list.  A privilidged user in the guest can
manipulate the mode list and that to trick qemu into oob reads, leading
to a DoS via segfault if that read access happens to hit unmapped memory.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20200225055920.17261-2-kraxel@redhat.com
This commit is contained in:
Gerd Hoffmann 2020-02-25 06:59:19 +01:00
parent cd8fef8d4b
commit 44b5c1ebfa
1 changed files with 1 additions and 1 deletions
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2
hw/display/qxl.c
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@ -2136,7 +2136,7 @@ static void qxl_realize_common(PCIQXLDevice *qxl, Error **errp)
pci_set_byte(&config[PCI_INTERRUPT_PIN], 1);
qxl->rom_size = qxl_rom_size();
memory_region_init_ram(&qxl->rom_bar, OBJECT(qxl), "qxl.vrom",
memory_region_init_rom(&qxl->rom_bar, OBJECT(qxl), "qxl.vrom",
qxl->rom_size, &error_fatal);
init_qxl_rom(qxl);
init_qxl_ram(qxl);