diff options
| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2014-01-17 13:12:34 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2014-01-22 14:02:16 +0100 |
| commit | b03b467944b3e88a36a33b5429425c42dbd5b8a0 (patch) | |
| tree | 57c5b36c72106e35e9ab9ca929946e5656373296 | |
| parent | 05e9181bdba4b1eb8f8eac5fd925df5223d16308 (diff) | |
s390/uaccess: test if current->mm is set before walking page tables
If get_fs() == USER_DS we better test if current->mm is not zero before
walking page tables.
The page table walk code would try to lock mm->page_table_lock, however
if mm is zero this might crash.
Now it is arguably incorrect trying to access userspace if current->mm
is zero, however we have seen that and s390 would be the only architecture
which would crash in such a case.
So we better make the page table walk code a bit more robust and report
always a fault instead.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
| -rw-r--r-- | arch/s390/lib/uaccess_pt.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/s390/lib/uaccess_pt.c b/arch/s390/lib/uaccess_pt.c index 0632dc50da7..5b77c341a1e 100644 --- a/arch/s390/lib/uaccess_pt.c +++ b/arch/s390/lib/uaccess_pt.c @@ -153,6 +153,8 @@ static __always_inline size_t __user_copy_pt(unsigned long uaddr, void *kptr, unsigned long offset, done, size, kaddr; void *from, *to; + if (!mm) + return n; done = 0; retry: spin_lock(&mm->page_table_lock); @@ -262,6 +264,8 @@ static size_t strnlen_user_pt(size_t count, const char __user *src) return 0; if (segment_eq(get_fs(), KERNEL_DS)) return strnlen_kernel(count, src); + if (!mm) + return 0; done = 0; retry: spin_lock(&mm->page_table_lock); @@ -323,6 +327,8 @@ static size_t copy_in_user_pt(size_t n, void __user *to, if (segment_eq(get_fs(), KERNEL_DS)) return copy_in_kernel(n, to, from); + if (!mm) + return n; done = 0; retry: spin_lock(&mm->page_table_lock); @@ -411,6 +417,8 @@ int futex_atomic_op_pt(int op, u32 __user *uaddr, int oparg, int *old) if (segment_eq(get_fs(), KERNEL_DS)) return __futex_atomic_op_pt(op, uaddr, oparg, old); + if (unlikely(!current->mm)) + return -EFAULT; spin_lock(¤t->mm->page_table_lock); uaddr = (u32 __force __user *) __dat_user_addr((__force unsigned long) uaddr, 1); @@ -448,6 +456,8 @@ int futex_atomic_cmpxchg_pt(u32 *uval, u32 __user *uaddr, if (segment_eq(get_fs(), KERNEL_DS)) return __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval); + if (unlikely(!current->mm)) + return -EFAULT; spin_lock(¤t->mm->page_table_lock); uaddr = (u32 __force __user *) __dat_user_addr((__force unsigned long) uaddr, 1); |