Robert Millan wrote:
On Fri, Mar 13, 2009 at 09:52:39PM +0100, phcoder wrote:
- grub_multiboot_payload_entry_offset = ehdr->e_entry -
phdr(lowest_segment)->p_vaddr;
+ for (i = 0; i < ehdr->e_phnum; i++)
+ if (phdr(i)->p_vaddr <= ehdr->e_entry
+ && phdr(i)->p_vaddr + phdr(i)->p_memsz > ehdr->e_entry)
+ grub_multiboot_payload_entry_offset = (ehdr->e_entry - phdr(i)->p_vaddr)
+ + (phdr(i)->p_paddr - phdr(lowest_segment)->p_paddr);
You need to handle the case in which grub_multiboot_payload_entry_offset is left
uninitialized (it needs to be initialized each time the multiboot command is
run, not just when the module is loaded).
module? actually it's when loading image. Perhaps you mean that
additional error check is necessary
--
Regards
Vladimir 'phcoder' Serbinenko
diff --git a/loader/i386/multiboot_elfxx.c b/loader/i386/multiboot_elfxx.c
index 801800c..706d44d 100644
--- a/loader/i386/multiboot_elfxx.c
+++ b/loader/i386/multiboot_elfxx.c
@@ -49,7 +49,7 @@ CONCAT(grub_multiboot_load_elf, XX) (grub_file_t file, void *buffer)
{
Elf_Ehdr *ehdr = (Elf_Ehdr *) buffer;
char *phdr_base;
- int lowest_segment = 0, highest_segment = 0;
+ int lowest_segment = -1, highest_segment = -1;
int i;
if (ehdr->e_ident[EI_CLASS] != ELFCLASSXX)
@@ -83,11 +83,18 @@ CONCAT(grub_multiboot_load_elf, XX) (grub_file_t file, void *buffer)
for (i = 0; i < ehdr->e_phnum; i++)
if (phdr(i)->p_type == PT_LOAD && phdr(i)->p_filesz != 0)
{
- if (phdr(i)->p_paddr < phdr(lowest_segment)->p_paddr)
+ /* Beware that segment 0 isn't necessarily loadable */
+ if (lowest_segment == -1
+ || phdr(i)->p_paddr < phdr(lowest_segment)->p_paddr)
lowest_segment = i;
- if (phdr(i)->p_paddr > phdr(highest_segment)->p_paddr)
+ if (highest_segment == -1
+ || phdr(i)->p_paddr > phdr(highest_segment)->p_paddr)
highest_segment = i;
}
+
+ if (lowest_segment == -1)
+ return grub_error (GRUB_ERR_BAD_OS, "ELF contains no loadable segments");
+
code_size = (phdr(highest_segment)->p_paddr + phdr(highest_segment)->p_memsz) - phdr(lowest_segment)->p_paddr;
grub_multiboot_payload_dest = phdr(lowest_segment)->p_paddr;
@@ -105,8 +112,8 @@ CONCAT(grub_multiboot_load_elf, XX) (grub_file_t file, void *buffer)
{
char *load_this_module_at = (char *) (grub_multiboot_payload_orig + (long) (phdr(i)->p_paddr - phdr(lowest_segment)->p_paddr));
- grub_dprintf ("multiboot_loader", "segment %d: paddr=0x%lx, memsz=0x%lx\n",
- i, (long) phdr(i)->p_paddr, (long) phdr(i)->p_memsz);
+ grub_dprintf ("multiboot_loader", "segment %d: paddr=0x%lx, memsz=0x%lx, vaddr=0x%lx\n",
+ i, (long) phdr(i)->p_paddr, (long) phdr(i)->p_memsz, (long) phdr(i)->p_vaddr);
if (grub_file_seek (file, (grub_off_t) phdr(i)->p_offset)
== (grub_off_t) -1)
@@ -124,11 +131,18 @@ CONCAT(grub_multiboot_load_elf, XX) (grub_file_t file, void *buffer)
}
}
- grub_multiboot_payload_entry_offset = ehdr->e_entry - phdr(lowest_segment)->p_vaddr;
+ for (i = 0; i < ehdr->e_phnum; i++)
+ if (phdr(i)->p_vaddr <= ehdr->e_entry
+ && phdr(i)->p_vaddr + phdr(i)->p_memsz > ehdr->e_entry)
+ {
+ grub_multiboot_payload_entry_offset = (ehdr->e_entry - phdr(i)->p_vaddr)
+ + (phdr(i)->p_paddr - phdr(lowest_segment)->p_paddr);
+ return grub_errno;
+ }
#undef phdr
- return grub_errno;
+ return grub_error (GRUB_ERR_BAD_OS, "entry point isn't in a segment");
}
#undef XX
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