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.
After the command 'dumpdtb' were introduced a couple of releases ago,
running it with any ARM machine that uses arm_load_dtb() will crash
QEMU.
Let's enable all arm_load_dtb() callers to use dumpdtb properly. Instead
of freeing 'fdt', assign it back to ms->fdt.
Note that all current callers (sbsa-ref.c, virt.c, xlnx-versal-virt.c)
are assigning ms->fdt before arm_load_dtb() is called, regardless of
whether the user is inputting an external FDT via '-dtb'. To avoid
leaking the board FDT if '-dtb' is used (since we're assigning ms->fdt
in the end), free ms->fdt before load_device_tree().
Cc: Peter Maydell <peter.mayd...@linaro.org>
Cc: qemu-...@nongnu.org
Fixes: bf353ad55590f ("qmp/hmp, device_tree.c: introduce dumpdtb")
Reported-by: Markus Armbruster <arm...@redhat.com>i
Signed-off-by: Daniel Henrique Barboza <danielhb...@gmail.com>
---
hw/arm/boot.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index 50e5141116..de18c0a969 100644
--- a/hw/arm/boot.c
+++ b/hw/arm/boot.c
@@ -549,6 +549,13 @@ int arm_load_dtb(hwaddr addr, const struct arm_boot_info
*binfo,
goto fail;
}
+ /*
+ * If we're here we won't be using the ms->fdt from the board.
+ * We'll assign a new ms->fdt at the end, so free it now to
+ * avoid leaking the board FDT.
+ */
+ g_free(ms->fdt);
+
fdt = load_device_tree(filename, &size);
if (!fdt) {
fprintf(stderr, "Couldn't open dtb file %s\n", filename);
@@ -689,7 +696,8 @@ int arm_load_dtb(hwaddr addr, const struct arm_boot_info
*binfo,
qemu_register_reset_nosnapshotload(qemu_fdt_randomize_seeds,
rom_ptr_for_as(as, addr, size));
- g_free(fdt);
+ /* Set ms->fdt for 'dumpdtb' QMP/HMP command */
+ ms->fdt = fdt;
return size;
--
2.39.2
