binfmt_elf_fdpic: Fix clear_user() error handling

clear_user() returns the number of bytes that could not be copied rather than
an error code.  So we should return -EFAULT rather than directly returning the
results.

Without this patch, positive values may be returned to elf_fdpic_map_file()
and the following error handlings do not function as expected.

1.
	ret = elf_fdpic_map_file_constdisp_on_uclinux(params, file, mm);
	if (ret < 0)
		return ret;
2.
	ret = elf_fdpic_map_file_by_direct_mmap(params, file, mm);
	if (ret < 0)
		return ret;
Signed-off-by: NTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NMike Frysinger <vapier@gentoo.org>
CC: Alexander Viro <viro@zeniv.linux.org.uk>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Daisuke HATAYAMA <d.hatayama@jp.fujitsu.com>
CC: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/binfmt_elf_fdpic.c

@@ -990,10 +990,9 @@ static int elf_fdpic_map_file_constdisp_on_uclinux(
 
 		/* clear any space allocated but not loaded */
 		if (phdr->p_filesz < phdr->p_memsz) {
-			ret = clear_user((void *) (seg->addr + phdr->p_filesz),
-					 phdr->p_memsz - phdr->p_filesz);
-			if (ret)
-				return ret;
+			if (clear_user((void *) (seg->addr + phdr->p_filesz),
+				       phdr->p_memsz - phdr->p_filesz))
+				return -EFAULT;
 		}
 
 		if (mm) {
@@ -1027,7 +1026,7 @@ static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *params,
 	struct elf32_fdpic_loadseg *seg;
 	struct elf32_phdr *phdr;
 	unsigned long load_addr, delta_vaddr;
-	int loop, dvset, ret;
+	int loop, dvset;
 
 	load_addr = params->load_addr;
 	delta_vaddr = 0;
@@ -1127,9 +1126,8 @@ static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *params,
 		 * PT_LOAD */
 		if (prot & PROT_WRITE && disp > 0) {
 			kdebug("clear[%d] ad=%lx sz=%lx", loop, maddr, disp);
-			ret = clear_user((void __user *) maddr, disp);
-			if (ret)
-				return ret;
+			if (clear_user((void __user *) maddr, disp))
+				return -EFAULT;
 			maddr += disp;
 		}
 
@@ -1164,19 +1162,17 @@ static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *params,
 		if (prot & PROT_WRITE && excess1 > 0) {
 			kdebug("clear[%d] ad=%lx sz=%lx",
 			       loop, maddr + phdr->p_filesz, excess1);
-			ret = clear_user((void __user *) maddr + phdr->p_filesz,
-					 excess1);
-			if (ret)
-				return ret;
+			if (clear_user((void __user *) maddr + phdr->p_filesz,
+				       excess1))
+				return -EFAULT;
 		}
 
 #else
 		if (excess > 0) {
 			kdebug("clear[%d] ad=%lx sz=%lx",
 			       loop, maddr + phdr->p_filesz, excess);
-			ret = clear_user((void *) maddr + phdr->p_filesz, excess);
-			if (ret)
-				return ret;
+			if (clear_user((void *) maddr + phdr->p_filesz, excess))
+				return -EFAULT;
 		}
 #endif