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: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Mike 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: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 2c5f9a0e5d72bb0357c45d5524186c14b3284bca..63039ed9576f75c396ed0dae71bec1e4abf53058 100644 (file)
--- a/fs/binfmt_elf_fdpic.c
+++ b/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