[PATCH 3/5] hw/core/loader: Provide rom_add_file() a 'max_size' argument

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

In commit d60fa42e8b we cared about loading ROMs smaller than
the underlying memory region (by zeroing the missing area) but
we forgot the case where a ROM file is bigger than the underlying
region.
Provide rom_add_file() a 'max_size' argument, and refuse loading
ROM files bigger than it.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 include/hw/loader.h | 12 ++++++------
 hw/core/loader.c    | 19 +++++++++++++------
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/include/hw/loader.h b/include/hw/loader.h
index a9eeea3952..99d690a628 100644
--- a/include/hw/loader.h
+++ b/include/hw/loader.h
@@ -254,7 +254,7 @@ extern bool option_rom_has_mr;
 extern bool rom_file_has_mr;
 
 int rom_add_file(const char *file, const char *fw_dir,
-                 hwaddr addr, int32_t bootindex,
+                 hwaddr addr, uint64_t max_len, int32_t bootindex,
                  bool option_rom, MemoryRegion *mr, AddressSpace *as);
 MemoryRegion *rom_add_blob(const char *name, const void *blob, size_t len,
                            size_t max_len, hwaddr addr,
@@ -292,16 +292,16 @@ int rom_copy(uint8_t *dest, hwaddr addr, size_t size);
 void *rom_ptr(hwaddr addr, size_t size);
 void hmp_info_roms(Monitor *mon, const QDict *qdict);
 
-#define rom_add_file_fixed(_f, _a, _i)          \
-    rom_add_file(_f, NULL, _a, _i, false, NULL, NULL)
+#define rom_add_file_fixed(_f, _a, _i) \
+    rom_add_file(_f, NULL, _a, -1, _i, false, NULL, NULL)
 #define rom_add_blob_fixed(_f, _b, _l, _a)      \
     rom_add_blob(_f, _b, _l, _l, _a, NULL, NULL, NULL, NULL, true)
 #define rom_add_file_mr(_f, _mr, _i)            \
-    rom_add_file(_f, NULL, 0, _i, false, _mr, NULL)
+    rom_add_file(_f, NULL, 0, -1, _i, false, _mr, NULL)
 #define rom_add_file_as(_f, _as, _i)            \
-    rom_add_file(_f, NULL, 0, _i, false, NULL, _as)
+    rom_add_file(_f, NULL, 0, -1, _i, false, NULL, _as)
 #define rom_add_file_fixed_as(_f, _a, _i, _as)          \
-    rom_add_file(_f, NULL, _a, _i, false, NULL, _as)
+    rom_add_file(_f, NULL, _a, -1, _i, false, NULL, _as)
 #define rom_add_blob_fixed_as(_f, _b, _l, _a, _as)      \
     rom_add_blob(_f, _b, _l, _l, _a, NULL, NULL, NULL, _as, true)
 
diff --git a/hw/core/loader.c b/hw/core/loader.c
index c67c483936..00436f1524 100644
--- a/hw/core/loader.c
+++ b/hw/core/loader.c
@@ -938,7 +938,7 @@ static void *rom_set_mr(Rom *rom, Object *owner, const char *name, bool ro)
 }
 
 int rom_add_file(const char *file, const char *fw_dir,
-                 hwaddr addr, int32_t bootindex,
+                 hwaddr addr, uint64_t max_len, int32_t bootindex,
                  bool option_rom, MemoryRegion *mr,
                  AddressSpace *as)
 {
@@ -974,14 +974,21 @@ int rom_add_file(const char *file, const char *fw_dir,
         rom->fw_file = g_strdup(file);
     }
     rom->addr     = addr;
-    rom->romsize  = lseek(fd, 0, SEEK_END);
-    if (rom->romsize == -1) {
+    rom->datasize = lseek(fd, 0, SEEK_END);
+    if (rom->datasize == -1) {
         fprintf(stderr, "rom: file %-20s: get size error: %s\n",
                 rom->name, strerror(errno));
         goto err;
     }
 
-    rom->datasize = rom->romsize;
+    rom->romsize = max_len ? max_len : rom->datasize;
+    if (rom->romsize < rom->datasize) {
+        fprintf(stderr,
+                "rom: file '%-20s' size too big: %zu (available: %zu)\n",
+                rom->name, rom->datasize, rom->romsize);
+        goto err;
+    }
+
     rom->data     = g_malloc0(rom->datasize);
     lseek(fd, 0, SEEK_SET);
     rc = read(fd, rom->data, rom->datasize);
@@ -1107,12 +1114,12 @@ int rom_add_elf_program(const char *name, GMappedFile *mapped_file, void *data,
 
 int rom_add_vga(const char *file)
 {
-    return rom_add_file(file, "vgaroms", 0, -1, true, NULL, NULL);
+    return rom_add_file(file, "vgaroms", 0, -1, -1, true, NULL, NULL);
 }
 
 int rom_add_option(const char *file, int32_t bootindex)
 {
-    return rom_add_file(file, "genroms", 0, bootindex, true, NULL, NULL);
+    return rom_add_file(file, "genroms", 0, -1, bootindex, true, NULL, NULL);
 }
 
 static void rom_reset(void *unused)
-- 
2.21.1