| Message ID | 20231202212217.243710-5-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | pstore: Initial use of cleanup.h | expand |
On Sat, Dec 02, 2023 at 01:22:15PM -0800, Kees Cook wrote: > static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos) > { > @@ -338,9 +339,8 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) > { > struct dentry *dentry; > struct inode *inode __free(iput) = NULL; > - int rc = 0; > char name[PSTORE_NAMELEN]; > - struct pstore_private *private, *pos; > + struct pstore_private *private __free(pstore_private) = NULL, *pos; > size_t size = record->size + record->ecc_notice_size; > > if (WARN_ON(!inode_is_locked(d_inode(root)))) > @@ -356,7 +356,6 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) > return -EEXIST; > } > > - rc = -ENOMEM; > inode = pstore_get_inode(root->d_sb); > if (!inode) > return -ENOMEM; > @@ -373,7 +372,7 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) > > dentry = d_alloc_name(root, name); > if (!dentry) > - goto fail_private; > + return -ENOMEM; > > private->dentry = dentry; > private->record = record; > @@ -386,13 +385,9 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) > > d_add(dentry, no_free_ptr(inode)); > > - list_add(&private->list, &records_list); > + list_add(&(no_free_ptr(private))->list, &records_list); That's really brittle. It critically depends upon having no failure exits past the assignment to ->i_private; once you've done that, you have transferred the ownership of that thing to the inode (look at your ->evict_inode()). But you can't say inode->i_private = no_free_ptr(private); since you are using private past that point.
On Sat, Dec 02, 2023 at 10:27:06PM +0000, Al Viro wrote: > On Sat, Dec 02, 2023 at 01:22:15PM -0800, Kees Cook wrote: > > > static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos) > > { > > @@ -338,9 +339,8 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) > > { > > struct dentry *dentry; > > struct inode *inode __free(iput) = NULL; > > - int rc = 0; > > char name[PSTORE_NAMELEN]; > > - struct pstore_private *private, *pos; > > + struct pstore_private *private __free(pstore_private) = NULL, *pos; > > size_t size = record->size + record->ecc_notice_size; > > > > if (WARN_ON(!inode_is_locked(d_inode(root)))) > > @@ -356,7 +356,6 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) > > return -EEXIST; > > } > > > > - rc = -ENOMEM; > > inode = pstore_get_inode(root->d_sb); > > if (!inode) > > return -ENOMEM; > > @@ -373,7 +372,7 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) > > > > dentry = d_alloc_name(root, name); > > if (!dentry) > > - goto fail_private; > > + return -ENOMEM; > > > > private->dentry = dentry; > > private->record = record; > > @@ -386,13 +385,9 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) > > > > d_add(dentry, no_free_ptr(inode)); > > > > - list_add(&private->list, &records_list); > > + list_add(&(no_free_ptr(private))->list, &records_list); > > That's really brittle. It critically depends upon having no failure > exits past the assignment to ->i_private; once you've done that, > you have transferred the ownership of that thing to the inode > (look at your ->evict_inode()). I guess so, but it was already that way, and it isn't assignment to i_private until everything else is "done", apart from adding to the dentry and the pstore internal list. > But you can't say > inode->i_private = no_free_ptr(private); > since you are using private past that point. True. How about this reordering: if (record->time.tv_sec) inode_set_mtime_to_ts(inode, inode_set_ctime_to_ts(inode, record->time)); list_add(&private->list, &records_list); inode->i_private = no_free_ptr(private); d_add(dentry, no_free_ptr(inode)); But none of this gets into how you'd like to see the iput handled. If you'd prefer, I can just define a pstore_iput handler and you don't have to look at it at all. :) -Kees
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c index 20a88e34ea7c..7d49f0c70dff 100644 --- a/fs/pstore/inode.c +++ b/fs/pstore/inode.c @@ -61,6 +61,7 @@ static void free_pstore_private(struct pstore_private *private) } kfree(private); } +DEFINE_FREE(pstore_private, struct pstore_private *, free_pstore_private(_T)); static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos) { @@ -338,9 +339,8 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) { struct dentry *dentry; struct inode *inode __free(iput) = NULL; - int rc = 0; char name[PSTORE_NAMELEN]; - struct pstore_private *private, *pos; + struct pstore_private *private __free(pstore_private) = NULL, *pos; size_t size = record->size + record->ecc_notice_size; if (WARN_ON(!inode_is_locked(d_inode(root)))) @@ -356,7 +356,6 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) return -EEXIST; } - rc = -ENOMEM; inode = pstore_get_inode(root->d_sb); if (!inode) return -ENOMEM; @@ -373,7 +372,7 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) dentry = d_alloc_name(root, name); if (!dentry) - goto fail_private; + return -ENOMEM; private->dentry = dentry; private->record = record; @@ -386,13 +385,9 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record) d_add(dentry, no_free_ptr(inode)); - list_add(&private->list, &records_list); + list_add(&(no_free_ptr(private))->list, &records_list); return 0; - -fail_private: - free_pstore_private(private); - return rc; } /*
Simplify error path when "private" needs to be freed. Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com> Cc: Tony Luck <tony.luck@intel.com> Cc: linux-hardening@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> --- fs/pstore/inode.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-)