Xen devel - Jun 2006 - [patch] improve ELF loader error messages

Provide more specific and helpful error messages during ELF loading.

Signed-off-by: Jimi Xenidis <jimix@watson.ibm.com>
Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>

diff -r 68928d1c8ab6 tools/libxc/xc_load_elf.c
--- a/tools/libxc/xc_load_elf.c	Fri Jun 30 15:24:44 2006 -0500
+++ b/tools/libxc/xc_load_elf.c	Fri Jun 30 15:40:09 2006 -0500
@@ -169,8 +169,11 @@ static int parseelfimage(const char *ima
     elf_pa_off_defined = (p != NULL);
     elf_pa_off = elf_pa_off_defined ? strtoull(p+17, &p, 0) : virt_base;
 
-    if ( elf_pa_off_defined && !virt_base_defined )
-        goto bad_image;
+    if ( elf_pa_off_defined && !virt_base_defined ) {
+        ERROR("Neither ELF_PADDR_OFFSET nor VIRT_BASE found in
__xen_guest"
+              " section.");
+        return -EINVAL;
+    }
 
     for ( h = 0; h < ehdr->e_phnum; h++ )
     {
@@ -178,8 +181,11 @@ static int parseelfimage(const char *ima
         if ( !is_loadable_phdr(phdr) )
             continue;
         vaddr = phdr->p_paddr - elf_pa_off + virt_base;
-        if ( (vaddr + phdr->p_memsz) < vaddr )
-            goto bad_image;
+        if ( (vaddr + phdr->p_memsz) < vaddr ) {
+            ERROR("ELF program header %d is too large.", h);
+            return -EINVAL;
+        }
+
         if ( vaddr < kernstart )
             kernstart = vaddr;
         if ( (vaddr + phdr->p_memsz) > kernend )
@@ -201,8 +207,10 @@ static int parseelfimage(const char *ima
     if ( (kernstart > kernend) ||
          (dsi->v_kernentry < kernstart) ||
          (dsi->v_kernentry > kernend) ||
-         (dsi->v_start > kernstart) )
-        goto bad_image;
+         (dsi->v_start > kernstart) ) {
+        ERROR("ELF start or entries are out of bounds.");
+        return -EINVAL;
+    }
 
     if ( (p = strstr(guestinfo, "BSD_SYMTAB")) != NULL )
         dsi->load_symtab = 1;
@@ -214,10 +222,6 @@ static int parseelfimage(const char *ima
     loadelfsymtab(image, 0, 0, NULL, dsi);
 
     return 0;
-
- bad_image:
-    ERROR("Malformed ELF image.");
-    return -EINVAL;
 }
 
 static int


-- 
Hollis Blanchard
IBM Linux Technology Center


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