[PATCH] hw/elf_ops: clear uninitialized segment space

[Laurent Vivier <laurent@vivier.eu>]

When the mem_size of the segment is bigger than the file_size,
and if this space doesn't overlap another segment, it needs
to be cleared.

This bug is very similar to the one we had for linux-user,
22d113b52f41 ("linux-user: Fix loading of BSS segments"),
where .bss section is encoded as an extension of the the data
one by setting the segment p_memsz > p_filesz.

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 include/hw/elf_ops.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/include/hw/elf_ops.h b/include/hw/elf_ops.h
index 6ee458e7bc3c..e3dcee3ee349 100644
--- a/include/hw/elf_ops.h
+++ b/include/hw/elf_ops.h
@@ -562,6 +562,23 @@ static int glue(load_elf, SZ)(const char *name, int fd,
                     if (res != MEMTX_OK) {
                         goto fail;
                     }
+                    /*
+                     * We need to zero'ify the space that is not copied
+                     * from file
+                     */
+                    if (file_size < mem_size) {
+                        static uint8_t zero[4096];
+                        uint64_t i;
+                        for (i = file_size; i < mem_size; i += sizeof(zero)) {
+                            res = address_space_write(
+                                         as ? as : &address_space_memory,
+                                         addr + i, MEMTXATTRS_UNSPECIFIED,
+                                         zero, MIN(sizeof(zero), mem_size - i));
+                            if (res != MEMTX_OK) {
+                                goto fail;
+                            }
+                        }
+                    }
                 }
             }
 
-- 
2.30.2