[PATCH 11/64] prctl: teach about range locking

From: Davidlohr Bueso
Date: Sun Feb 04 2018 - 20:42:45 EST


From: Davidlohr Bueso <dave@xxxxxxxxxxxx>

And pass along pointers where needed. No changes in
semantics by using mm locking helpers.

Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
---
kernel/sys.c | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/kernel/sys.c b/kernel/sys.c
index 31a2866b7abd..a9c659c42bd6 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1769,6 +1769,7 @@ static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
struct file *old_exe, *exe_file;
struct inode *inode;
int err;
+ DEFINE_RANGE_LOCK_FULL(mmrange);

exe = fdget(fd);
if (!exe.file)
@@ -1797,7 +1798,7 @@ static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
if (exe_file) {
struct vm_area_struct *vma;

- down_read(&mm->mmap_sem);
+ mm_read_lock(mm, &mmrange);
for (vma = mm->mmap; vma; vma = vma->vm_next) {
if (!vma->vm_file)
continue;
@@ -1806,7 +1807,7 @@ static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
goto exit_err;
}

- up_read(&mm->mmap_sem);
+ mm_read_unlock(mm, &mmrange);
fput(exe_file);
}

@@ -1820,7 +1821,7 @@ static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
fdput(exe);
return err;
exit_err:
- up_read(&mm->mmap_sem);
+ mm_read_unlock(mm, &mmrange);
fput(exe_file);
goto exit;
}
@@ -1923,6 +1924,7 @@ static int prctl_set_mm_map(int opt, const void __user *addr, unsigned long data
unsigned long user_auxv[AT_VECTOR_SIZE];
struct mm_struct *mm = current->mm;
int error;
+ DEFINE_RANGE_LOCK_FULL(mmrange);

BUILD_BUG_ON(sizeof(user_auxv) != sizeof(mm->saved_auxv));
BUILD_BUG_ON(sizeof(struct prctl_mm_map) > 256);
@@ -1959,7 +1961,7 @@ static int prctl_set_mm_map(int opt, const void __user *addr, unsigned long data
return error;
}

- down_write(&mm->mmap_sem);
+ mm_write_lock(mm, &mmrange);

/*
* We don't validate if these members are pointing to
@@ -1996,7 +1998,7 @@ static int prctl_set_mm_map(int opt, const void __user *addr, unsigned long data
if (prctl_map.auxv_size)
memcpy(mm->saved_auxv, user_auxv, sizeof(user_auxv));

- up_write(&mm->mmap_sem);
+ mm_write_unlock(mm, &mmrange);
return 0;
}
#endif /* CONFIG_CHECKPOINT_RESTORE */
@@ -2038,6 +2040,7 @@ static int prctl_set_mm(int opt, unsigned long addr,
struct prctl_mm_map prctl_map;
struct vm_area_struct *vma;
int error;
+ DEFINE_RANGE_LOCK_FULL(mmrange);

if (arg5 || (arg4 && (opt != PR_SET_MM_AUXV &&
opt != PR_SET_MM_MAP &&
@@ -2063,7 +2066,7 @@ static int prctl_set_mm(int opt, unsigned long addr,

error = -EINVAL;

- down_write(&mm->mmap_sem);
+ mm_write_lock(mm, &mmrange);
vma = find_vma(mm, addr);

prctl_map.start_code = mm->start_code;
@@ -2156,7 +2159,7 @@ static int prctl_set_mm(int opt, unsigned long addr,

error = 0;
out:
- up_write(&mm->mmap_sem);
+ mm_write_unlock(mm, &mmrange);
return error;
}

@@ -2196,6 +2199,7 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
struct task_struct *me = current;
unsigned char comm[sizeof(me->comm)];
long error;
+ DEFINE_RANGE_LOCK_FULL(mmrange);

error = security_task_prctl(option, arg2, arg3, arg4, arg5);
if (error != -ENOSYS)
@@ -2379,13 +2383,13 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
case PR_SET_THP_DISABLE:
if (arg3 || arg4 || arg5)
return -EINVAL;
- if (down_write_killable(&me->mm->mmap_sem))
+ if (mm_write_lock_killable(me->mm, &mmrange))
return -EINTR;
if (arg2)
set_bit(MMF_DISABLE_THP, &me->mm->flags);
else
clear_bit(MMF_DISABLE_THP, &me->mm->flags);
- up_write(&me->mm->mmap_sem);
+ mm_write_unlock(me->mm, &mmrange);
break;
case PR_MPX_ENABLE_MANAGEMENT:
if (arg2 || arg3 || arg4 || arg5)
--
2.13.6