At this moment, arm_load_dtb() can free machine->fdt when
binfo->dtb_filename is NULL. If there's no 'dtb_filename', 'fdt' will be
retrieved by binfo->get_dtb(). If get_dtb() returns machine->fdt, as is
the case of machvirt_dtb() from hw/arm/virt.c, fdt now has a pointer to
machine->fdt. And, in that case, the existing g_free(fdt) at the end of
arm_load_dtb() will make machine->fdt point to an invalid memory region.
This is not an issue right now because there's no code that access
machine->fdt after arm_load_dtb(), but we're going to add a couple do
FDT HMP commands that will rely on machine->fdt being valid.
Instead of freeing 'fdt' at the end of arm_load_dtb(), assign it to
machine->fdt. This will allow the FDT of ARM machines that relies on
arm_load_dtb() to be accessed later on.
Since all ARM machines allocates the FDT only once, we don't need to
worry about leaking the existing FDT during a machine reset (which is
something that other machines have to look after, e.g. the ppc64 pSeries
Cc: Peter Maydell <email@example.com>
Signed-off-by: Daniel Henrique Barboza <firstname.lastname@example.org>
hw/arm/boot.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index ada2717f76..9f5ceb62d2 100644
@@ -684,7 +684,13 @@ int arm_load_dtb(hwaddr addr, const struct arm_boot_info
rom_add_blob_fixed_as("dtb", fdt, size, addr, as);
+ * Update the ms->fdt pointer to enable support for 'dumpdtb'
+ * and 'info fdt' commands. Use fdt_pack() to shrink the blob
+ * size we're going to store.
+ ms->fdt = fdt;