Instead of taking mm->mmap_sem inside prctl_set_mm_exe_file move
it out of and rename the helper to prctl_set_mm_exe_file_locked.
This will allow to reuse this function in a next patch.
Signed-off-by: Cyrill Gorcunov <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andrew Vagin <[email protected]>
Cc: Eric W. Biederman <[email protected]>
Cc: Serge Hallyn <[email protected]>
Cc: Pavel Emelyanov <[email protected]>
Cc: Vasiliy Kulikov <[email protected]>
Cc: KAMEZAWA Hiroyuki <[email protected]>
Cc: Michael Kerrisk <[email protected]>
---
kernel/sys.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
Index: linux-2.6.git/kernel/sys.c
===================================================================
--- linux-2.6.git.orig/kernel/sys.c
+++ linux-2.6.git/kernel/sys.c
@@ -1628,12 +1628,14 @@ SYSCALL_DEFINE1(umask, int, mask)
return mask;
}
-static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
+static int prctl_set_mm_exe_file_locked(struct mm_struct *mm, unsigned int fd)
{
struct fd exe;
struct inode *inode;
int err;
+ VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
+
exe = fdget(fd);
if (!exe.file)
return -EBADF;
@@ -1654,8 +1656,6 @@ static int prctl_set_mm_exe_file(struct
if (err)
goto exit;
- down_write(&mm->mmap_sem);
-
/*
* Forbid mm->exe_file change if old file still mapped.
*/
@@ -1667,7 +1667,7 @@ static int prctl_set_mm_exe_file(struct
if (vma->vm_file &&
path_equal(&vma->vm_file->f_path,
&mm->exe_file->f_path))
- goto exit_unlock;
+ goto exit;
}
/*
@@ -1678,13 +1678,10 @@ static int prctl_set_mm_exe_file(struct
*/
err = -EPERM;
if (test_and_set_bit(MMF_EXE_FILE_CHANGED, &mm->flags))
- goto exit_unlock;
+ goto exit;
err = 0;
set_mm_exe_file(mm, exe.file); /* this grabs a reference to exe.file */
-exit_unlock:
- up_write(&mm->mmap_sem);
-
exit:
fdput(exe);
return err;
@@ -1704,8 +1701,12 @@ static int prctl_set_mm(int opt, unsigne
if (!capable(CAP_SYS_RESOURCE))
return -EPERM;
- if (opt == PR_SET_MM_EXE_FILE)
- return prctl_set_mm_exe_file(mm, (unsigned int)addr);
+ if (opt == PR_SET_MM_EXE_FILE) {
+ down_write(&mm->mmap_sem);
+ error = prctl_set_mm_exe_file_locked(mm, (unsigned int)addr);
+ up_write(&mm->mmap_sem);
+ return error;
+ }
if (addr >= TASK_SIZE || addr < mmap_min_addr)
return -EINVAL;