[PATCH v2] generic-loader: check that binary file target location exists

[Damien Hedde]

When loading a binary file, we only check if it is smaller than the
ram_size. It does not really check if the file will be loaded at an
existing location (if there is nothing at the target address, it will
"fail" silently later). It prevents loading a binary blob bigger than
ram_size too even if the target location is big enough.

Replace this check by looking for the target memory region size and
prevent loading a bigger file than the available space.

Get rid of "hw/boards.h" include, since we needed it only to access
`current_machine`.

Signed-off-by: Damien Hedde <damien.hedde@greensocs.com>
---

Hi,

This is an updated version implementing what we discussed in v1.

This can be tested easily, eg, using opentitan machine which has a 64K ram
located at 0x10000000.

the following works (we a blob corresponding to the whole ram)
| $ dd bs=1K count=64 if=/dev/zero of=blob.bin
| $ qemu-system-riscv32 -display none -M opentitan -device 
loader,addr=0x10000000,file=blob.bin

but this command fails because we load a blob which is too big
| $ dd bs=1K count=64 if=/dev/zero of=blob.bin
| $ qemu-system-riscv32 -display none -M opentitan -device 
loader,addr=0x10001000,file=blob.bin
| qemu-system-riscv32: -device loader,addr=0x10001000,file=blob.bin: Cannot 
load specified image blob.bin

and this command fails too (we load a blob at an unmapped location)
| $ dd bs=1K count=64 if=/dev/zero of=blob.bin
| $ qemu-system-riscv32 -display none -M opentitan -device 
loader,addr=0x0,file=blob.bin
| qemu-system-riscv32: -device loader,addr=0x0,file=blob.bin: Address 0x0 does 
not exists

Thanks,
Damien

v2:
 + instead of disabling the ram_size check, look for the target

v1: https://lists.nongnu.org/archive/html/qemu-devel/2021-10/msg01077.html

See also the original discussion about generic-loader:
https://lists.gnu.org/archive/html/qemu-devel/2016-02/msg04668.html
https://lists.gnu.org/archive/html/qemu-devel/2016-02/msg04681.html
---
 hw/core/generic-loader.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/hw/core/generic-loader.c b/hw/core/generic-loader.c
index d14f932eea..88d3f9fd56 100644
--- a/hw/core/generic-loader.c
+++ b/hw/core/generic-loader.c
@@ -34,7 +34,6 @@
 #include "hw/core/cpu.h"
 #include "sysemu/dma.h"
 #include "sysemu/reset.h"
-#include "hw/boards.h"
 #include "hw/loader.h"
 #include "hw/qdev-properties.h"
 #include "qapi/error.h"
@@ -153,8 +152,23 @@ static void generic_loader_realize(DeviceState *dev, Error 
**errp)
         }
 
         if (size < 0 || s->force_raw) {
-            /* Default to the maximum size being the machine's ram size */
-            size = load_image_targphys_as(s->file, s->addr, 
current_machine->ram_size, as);
+            MemoryRegion *root = as ? as->root : get_system_memory();
+            MemoryRegionSection mrs;
+            uint64_t avail = 0;
+
+            mrs = memory_region_find(root, s->addr, 1);
+
+            if (mrs.mr) {
+                avail = int128_get64(mrs.mr->size) - mrs.offset_within_region;
+                memory_region_unref(mrs.mr);
+            } else {
+                error_setg(errp, "Address 0x%" PRIx64 " does not exists",
+                           s->addr);
+                return;
+            }
+
+            /* Limit the file size to the memory region space */
+            size = load_image_targphys_as(s->file, s->addr, avail, as);
         } else {
             s->addr = entry;
         }
-- 
2.33.0