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authorLinus Torvalds <torvalds@linux-foundation.org>2016-10-14 18:19:05 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-10-14 18:19:05 -0700
commitb26b5ef5ec7eab0e1d84c5b281e87b2f2a5e0586 (patch)
tree3fd57787765f05a19b85b384bd2a68cb4f9276d4 /fs
parent87dbe42a16b654e33665756c63e96c0fa73eb003 (diff)
parent2692a71bbd40160165e89d5505c5c28144ec5a42 (diff)
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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull more misc uaccess and vfs updates from Al Viro: "The rest of the stuff from -next (more uaccess work) + assorted fixes" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: score: traps: Add missing include file to fix build error fs/super.c: don't fool lockdep in freeze_super() and thaw_super() paths fs/super.c: fix race between freeze_super() and thaw_super() overlayfs: Fix setting IOP_XATTR flag iov_iter: kernel-doc import_iovec() and rw_copy_check_uvector() blackfin: no access_ok() for __copy_{to,from}_user() arm64: don't zero in __copy_from_user{,_inatomic} arm: don't zero in __copy_from_user_inatomic()/__copy_from_user() arc: don't leak bits of kernel stack into coredump alpha: get rid of tail-zeroing in __copy_user()
Diffstat (limited to 'fs')
-rw-r--r--fs/overlayfs/super.c11
-rw-r--r--fs/read_write.c29
-rw-r--r--fs/super.c43
3 files changed, 63 insertions, 20 deletions
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 89182c4e2e30..bcf3965be819 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1303,6 +1303,12 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
if (!oe)
goto out_put_cred;
+ sb->s_magic = OVERLAYFS_SUPER_MAGIC;
+ sb->s_op = &ovl_super_operations;
+ sb->s_xattr = ovl_xattr_handlers;
+ sb->s_fs_info = ufs;
+ sb->s_flags |= MS_POSIXACL | MS_NOREMOTELOCK;
+
root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR));
if (!root_dentry)
goto out_free_oe;
@@ -1326,12 +1332,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
ovl_inode_init(d_inode(root_dentry), realinode, !!upperpath.dentry);
ovl_copyattr(realinode, d_inode(root_dentry));
- sb->s_magic = OVERLAYFS_SUPER_MAGIC;
- sb->s_op = &ovl_super_operations;
- sb->s_xattr = ovl_xattr_handlers;
sb->s_root = root_dentry;
- sb->s_fs_info = ufs;
- sb->s_flags |= MS_POSIXACL | MS_NOREMOTELOCK;
return 0;
diff --git a/fs/read_write.c b/fs/read_write.c
index 66215a7b17cf..190e0d362581 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -730,6 +730,35 @@ static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
/* A write operation does a read from user space and vice versa */
#define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
+/**
+ * rw_copy_check_uvector() - Copy an array of &struct iovec from userspace
+ * into the kernel and check that it is valid.
+ *
+ * @type: One of %CHECK_IOVEC_ONLY, %READ, or %WRITE.
+ * @uvector: Pointer to the userspace array.
+ * @nr_segs: Number of elements in userspace array.
+ * @fast_segs: Number of elements in @fast_pointer.
+ * @fast_pointer: Pointer to (usually small on-stack) kernel array.
+ * @ret_pointer: (output parameter) Pointer to a variable that will point to
+ * either @fast_pointer, a newly allocated kernel array, or NULL,
+ * depending on which array was used.
+ *
+ * This function copies an array of &struct iovec of @nr_segs from
+ * userspace into the kernel and checks that each element is valid (e.g.
+ * it does not point to a kernel address or cause overflow by being too
+ * large, etc.).
+ *
+ * As an optimization, the caller may provide a pointer to a small
+ * on-stack array in @fast_pointer, typically %UIO_FASTIOV elements long
+ * (the size of this array, or 0 if unused, should be given in @fast_segs).
+ *
+ * @ret_pointer will always point to the array that was used, so the
+ * caller must take care not to call kfree() on it e.g. in case the
+ * @fast_pointer array was used and it was allocated on the stack.
+ *
+ * Return: The total number of bytes covered by the iovec array on success
+ * or a negative error code on error.
+ */
ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
unsigned long nr_segs, unsigned long fast_segs,
struct iovec *fast_pointer,
diff --git a/fs/super.c b/fs/super.c
index c2ff475c1711..c183835566c1 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1269,25 +1269,34 @@ EXPORT_SYMBOL(__sb_start_write);
static void sb_wait_write(struct super_block *sb, int level)
{
percpu_down_write(sb->s_writers.rw_sem + level-1);
- /*
- * We are going to return to userspace and forget about this lock, the
- * ownership goes to the caller of thaw_super() which does unlock.
- *
- * FIXME: we should do this before return from freeze_super() after we
- * called sync_filesystem(sb) and s_op->freeze_fs(sb), and thaw_super()
- * should re-acquire these locks before s_op->unfreeze_fs(sb). However
- * this leads to lockdep false-positives, so currently we do the early
- * release right after acquire.
- */
- percpu_rwsem_release(sb->s_writers.rw_sem + level-1, 0, _THIS_IP_);
}
-static void sb_freeze_unlock(struct super_block *sb)
+/*
+ * We are going to return to userspace and forget about these locks, the
+ * ownership goes to the caller of thaw_super() which does unlock().
+ */
+static void lockdep_sb_freeze_release(struct super_block *sb)
+{
+ int level;
+
+ for (level = SB_FREEZE_LEVELS - 1; level >= 0; level--)
+ percpu_rwsem_release(sb->s_writers.rw_sem + level, 0, _THIS_IP_);
+}
+
+/*
+ * Tell lockdep we are holding these locks before we call ->unfreeze_fs(sb).
+ */
+static void lockdep_sb_freeze_acquire(struct super_block *sb)
{
int level;
for (level = 0; level < SB_FREEZE_LEVELS; ++level)
percpu_rwsem_acquire(sb->s_writers.rw_sem + level, 0, _THIS_IP_);
+}
+
+static void sb_freeze_unlock(struct super_block *sb)
+{
+ int level;
for (level = SB_FREEZE_LEVELS - 1; level >= 0; level--)
percpu_up_write(sb->s_writers.rw_sem + level);
@@ -1379,10 +1388,11 @@ int freeze_super(struct super_block *sb)
}
}
/*
- * This is just for debugging purposes so that fs can warn if it
- * sees write activity when frozen is set to SB_FREEZE_COMPLETE.
+ * For debugging purposes so that fs can warn if it sees write activity
+ * when frozen is set to SB_FREEZE_COMPLETE, and for thaw_super().
*/
sb->s_writers.frozen = SB_FREEZE_COMPLETE;
+ lockdep_sb_freeze_release(sb);
up_write(&sb->s_umount);
return 0;
}
@@ -1399,7 +1409,7 @@ int thaw_super(struct super_block *sb)
int error;
down_write(&sb->s_umount);
- if (sb->s_writers.frozen == SB_UNFROZEN) {
+ if (sb->s_writers.frozen != SB_FREEZE_COMPLETE) {
up_write(&sb->s_umount);
return -EINVAL;
}
@@ -1409,11 +1419,14 @@ int thaw_super(struct super_block *sb)
goto out;
}
+ lockdep_sb_freeze_acquire(sb);
+
if (sb->s_op->unfreeze_fs) {
error = sb->s_op->unfreeze_fs(sb);
if (error) {
printk(KERN_ERR
"VFS:Filesystem thaw failed\n");
+ lockdep_sb_freeze_release(sb);
up_write(&sb->s_umount);
return error;
}