diff options
Diffstat (limited to 'ipc')
| -rw-r--r-- | ipc/shm.c | 45 |
1 files changed, 21 insertions, 24 deletions
diff --git a/ipc/shm.c b/ipc/shm.c index fefa00d310fb..d8a38b3be5dd 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -1366,15 +1366,14 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, struct shmid_kernel *shp; unsigned long addr = (unsigned long)shmaddr; unsigned long size; - struct file *file; + struct file *file, *base; int err; unsigned long flags = MAP_SHARED; unsigned long prot; int acc_mode; struct ipc_namespace *ns; struct shm_file_data *sfd; - struct path path; - fmode_t f_mode; + int f_flags; unsigned long populate = 0; err = -EINVAL; @@ -1407,11 +1406,11 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, if (shmflg & SHM_RDONLY) { prot = PROT_READ; acc_mode = S_IRUGO; - f_mode = FMODE_READ; + f_flags = O_RDONLY; } else { prot = PROT_READ | PROT_WRITE; acc_mode = S_IRUGO | S_IWUGO; - f_mode = FMODE_READ | FMODE_WRITE; + f_flags = O_RDWR; } if (shmflg & SHM_EXEC) { prot |= PROT_EXEC; @@ -1447,46 +1446,44 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, goto out_unlock; } - path = shp->shm_file->f_path; - path_get(&path); + /* + * We need to take a reference to the real shm file to prevent the + * pointer from becoming stale in cases where the lifetime of the outer + * file extends beyond that of the shm segment. It's not usually + * possible, but it can happen during remap_file_pages() emulation as + * that unmaps the memory, then does ->mmap() via file reference only. + * We'll deny the ->mmap() if the shm segment was since removed, but to + * detect shm ID reuse we need to compare the file pointers. + */ + base = get_file(shp->shm_file); shp->shm_nattch++; - size = i_size_read(d_inode(path.dentry)); + size = i_size_read(file_inode(base)); ipc_unlock_object(&shp->shm_perm); rcu_read_unlock(); err = -ENOMEM; sfd = kzalloc(sizeof(*sfd), GFP_KERNEL); if (!sfd) { - path_put(&path); + fput(base); goto out_nattch; } - file = alloc_file(&path, f_mode, - is_file_hugepages(shp->shm_file) ? + file = alloc_file_clone(base, f_flags, + is_file_hugepages(base) ? &shm_file_operations_huge : &shm_file_operations); err = PTR_ERR(file); if (IS_ERR(file)) { kfree(sfd); - path_put(&path); + fput(base); goto out_nattch; } - file->private_data = sfd; - file->f_mapping = shp->shm_file->f_mapping; sfd->id = shp->shm_perm.id; sfd->ns = get_ipc_ns(ns); - /* - * We need to take a reference to the real shm file to prevent the - * pointer from becoming stale in cases where the lifetime of the outer - * file extends beyond that of the shm segment. It's not usually - * possible, but it can happen during remap_file_pages() emulation as - * that unmaps the memory, then does ->mmap() via file reference only. - * We'll deny the ->mmap() if the shm segment was since removed, but to - * detect shm ID reuse we need to compare the file pointers. - */ - sfd->file = get_file(shp->shm_file); + sfd->file = base; sfd->vm_ops = NULL; + file->private_data = sfd; err = security_mmap_file(file, prot, flags); if (err) |