[PATCH] binfmt_elf: handle partial reads gracefully

Make sure kernel reads full size of elf data.  Error out if mmap fails
when mapping any sections of the executable.  Make sure interpreter
string is NULL terminated. 
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/binfmt_elf.c

@@ -335,9 +335,12 @@ static unsigned long load_elf_interp(struct elfhdr * interp_elf_ex,
 		goto out;
 
 	retval = kernel_read(interpreter,interp_elf_ex->e_phoff,(char *)elf_phdata,size);
-	error = retval;
-	if (retval < 0)
+	error = -EIO;
+	if (retval != size) {
+		if (retval < 0)
+			error = retval;	
 		goto out_close;
+	}
 
 	eppnt = elf_phdata;
 	for (i=0; i<interp_elf_ex->e_phnum; i++, eppnt++) {
@@ -532,8 +535,11 @@ static int load_elf_binary(struct linux_binprm * bprm, struct pt_regs * regs)
 		goto out;
 
 	retval = kernel_read(bprm->file, loc->elf_ex.e_phoff, (char *) elf_phdata, size);
-	if (retval < 0)
+	if (retval != size) {
+		if (retval >= 0)
+			retval = -EIO;
 		goto out_free_ph;
+	}
 
 	files = current->files;		/* Refcounted so ok */
 	retval = unshare_files();
@@ -580,8 +586,14 @@ static int load_elf_binary(struct linux_binprm * bprm, struct pt_regs * regs)
 			retval = kernel_read(bprm->file, elf_ppnt->p_offset,
 					   elf_interpreter,
 					   elf_ppnt->p_filesz);
-			if (retval < 0)
+			if (retval != elf_ppnt->p_filesz) {
+				if (retval >= 0)
+					retval = -EIO;
 				goto out_free_interp;
+			}
+			/* make sure path is NULL terminated */
+			elf_interpreter[elf_ppnt->p_filesz - 1] = '\0';
+
 			/* If the program interpreter is one of these two,
 			 * then assume an iBCS2 image. Otherwise assume
 			 * a native linux image.
@@ -616,8 +628,11 @@ static int load_elf_binary(struct linux_binprm * bprm, struct pt_regs * regs)
 			if (IS_ERR(interpreter))
 				goto out_free_interp;
 			retval = kernel_read(interpreter, 0, bprm->buf, BINPRM_BUF_SIZE);
-			if (retval < 0)
+			if (retval != BINPRM_BUF_SIZE) {
+				if (retval >= 0)
+					retval = -EIO;
 				goto out_free_dentry;
+			}
 
 			/* Get the exec headers */
 			loc->interp_ex = *((struct exec *) bprm->buf);
@@ -776,8 +791,10 @@ static int load_elf_binary(struct linux_binprm * bprm, struct pt_regs * regs)
 		}
 
 		error = elf_map(bprm->file, load_bias + vaddr, elf_ppnt, elf_prot, elf_flags);
-		if (BAD_ADDR(error))
-			continue;
+		if (BAD_ADDR(error)) {
+			send_sig(SIGKILL, current, 0);
+			goto out_free_dentry;
+		}
 
 		if (!load_addr_set) {
 			load_addr_set = 1;