Guard check in module loader against integer overflow

The check: if (len < hdr->e_shoff + hdr->e_shnum * sizeof(Elf_Shdr)) may not work if there's an overflow in the right-hand side of the condition. Signed-off-by: David Howells <[email protected]> Signed-off-by: Rusty Russell <[email protected]>
VadimAlexeev · May 23, 2012 · ef26a5a · ef26a5a
1 parent 3c7ec94
commit ef26a5a
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/kernel/module.c b/kernel/module.c
@@ -2429,7 +2429,8 @@ static int copy_and_check(struct load_info *info,
 		goto free_hdr;
 	}
 
-	if (len < hdr->e_shoff + hdr->e_shnum * sizeof(Elf_Shdr)) {
+	if (hdr->e_shoff >= len ||
+	    hdr->e_shnum * sizeof(Elf_Shdr) > len - hdr->e_shoff) {
 		err = -ENOEXEC;
 		goto free_hdr;
 	}