diff options
| author | Amir Goldstein <amir73il@gmail.com> | 2023-11-20 15:43:34 +0200 |
|---|---|---|
| committer | Amir Goldstein <amir73il@gmail.com> | 2023-11-20 16:01:45 +0200 |
| commit | 2c3ef4f89ced1a9d3a6fd4f6457be5c440c89362 (patch) | |
| tree | 3317991409c4d11aa8805e67ad5108905722c0be /fs/overlayfs | |
| parent | 02d70090e0e020eff440dbe51e93fe2fc94d9835 (diff) | |
ovl: initialize ovl_copy_up_ctx.destname inside ovl_do_copy_up()
The ->destname member of struct ovl_copy_up_ctx is initialized inside
ovl_copy_up_one() to ->d_name of the overlayfs dentry being copied up
and then it may be overridden by index name inside ovl_do_copy_up().
ovl_inode_lock() in ovl_copy_up_start() and ovl_copy_up() in ovl_rename()
effectively stabilze ->d_name of the overlayfs dentry being copied up,
but ovl_inode_lock() is not held when ->d_name is being read.
It is not a correctness bug, because if ovl_do_copy_up() races with
ovl_rename() and ctx.destname is freed, we will not end up calling
ovl_do_copy_up() with the dead name reference.
The code becomes much easier to understand and to document if the
initialization of c->destname is always done inside ovl_do_copy_up(),
either to the index entry name, or to the overlay dentry ->d_name.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Diffstat (limited to 'fs/overlayfs')
| -rw-r--r-- | fs/overlayfs/copy_up.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index 4382881b0709..500c555792ff 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -930,6 +930,13 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c) goto out_free_fh; } else { /* + * c->dentry->d_name is stabilzed by ovl_copy_up_start(), + * because if we got here, it means that c->dentry has no upper + * alias and changing ->d_name means going through ovl_rename() + * that will call ovl_copy_up() on source and target dentry. + */ + c->destname = c->dentry->d_name; + /* * Mark parent "impure" because it may now contain non-pure * upper */ @@ -1109,7 +1116,6 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, if (parent) { ovl_path_upper(parent, &parentpath); ctx.destdir = parentpath.dentry; - ctx.destname = dentry->d_name; err = vfs_getattr(&parentpath, &ctx.pstat, STATX_ATIME | STATX_MTIME, |