diff options
Diffstat (limited to 'ipc/shm.c')
| -rw-r--r-- | ipc/shm.c | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/ipc/shm.c b/ipc/shm.c index 01454796ba3c..19633b4a2350 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -219,7 +219,8 @@ static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp) if (!is_file_hugepages(shm_file)) shmem_lock(shm_file, 0, shp->mlock_user); else if (shp->mlock_user) - user_shm_unlock(file_inode(shm_file)->i_size, shp->mlock_user); + user_shm_unlock(i_size_read(file_inode(shm_file)), + shp->mlock_user); fput(shm_file); ipc_rcu_putref(shp, shm_rcu_free); } @@ -1229,6 +1230,7 @@ SYSCALL_DEFINE1(shmdt, char __user *, shmaddr) int retval = -EINVAL; #ifdef CONFIG_MMU loff_t size = 0; + struct file *file; struct vm_area_struct *next; #endif @@ -1245,7 +1247,8 @@ SYSCALL_DEFINE1(shmdt, char __user *, shmaddr) * started at address shmaddr. It records it's size and then unmaps * it. * - Then it unmaps all shm vmas that started at shmaddr and that - * are within the initially determined size. + * are within the initially determined size and that are from the + * same shm segment from which we determined the size. * Errors from do_munmap are ignored: the function only fails if * it's called with invalid parameters or if it's called to unmap * a part of a vma. Both calls in this function are for full vmas, @@ -1271,8 +1274,14 @@ SYSCALL_DEFINE1(shmdt, char __user *, shmaddr) if ((vma->vm_ops == &shm_vm_ops) && (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) { - - size = file_inode(vma->vm_file)->i_size; + /* + * Record the file of the shm segment being + * unmapped. With mremap(), someone could place + * page from another segment but with equal offsets + * in the range we are unmapping. + */ + file = vma->vm_file; + size = i_size_read(file_inode(vma->vm_file)); do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start); /* * We discovered the size of the shm segment, so @@ -1298,8 +1307,8 @@ SYSCALL_DEFINE1(shmdt, char __user *, shmaddr) /* finding a matching vma now does not alter retval */ if ((vma->vm_ops == &shm_vm_ops) && - (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) - + ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) && + (vma->vm_file == file)) do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start); vma = next; } |