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pstore: Fix double-free in pstore_mkfile() failure path 

The pstore_mkfile() function is passed a pointer to a struct
pstore_record. On success it consumes this 'record' pointer and
references it from the created inode.

On failure, however, it may or may not free the record. There are even
two different code paths which return -ENOMEM -- one of which does and
the other doesn't free the record.

Make the behaviour deterministic by never consuming and freeing the
record when returning failure, allowing the caller to do the cleanup
consistently.

Signed-off-by: Norbert Manthey <nmanthey@amazon.de>
Link: https://lore.kernel.org/r/1562331960-26198-1-git-send-email-nmanthey@amazon.de
Fixes: 83f70f0769 ("pstore: Do not duplicate record metadata")
Fixes: 1dfff7dd67 ("pstore: Pass record contents instead of copying")
Cc: stable@vger.kernel.org
[kees: also move "private" allocation location, rename inode cleanup label]
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Norbert Manthey 2019-07-05 15:06:00 +02:00 committed by Kees Cook
parent fa1af7583e
commit 4c6d80e114
1 changed files with 6 additions and 7 deletions
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13
fs/pstore/inode.c
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@ -318,22 +318,21 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
goto fail;
inode->i_mode = S_IFREG | 0444;
inode->i_fop = &pstore_file_operations;
private = kzalloc(sizeof(*private), GFP_KERNEL);
if (!private)
goto fail_alloc;
private->record = record;
scnprintf(name, sizeof(name), "%s-%s-%llu%s",
pstore_type_to_name(record->type),
record->psi->name, record->id,
record->compressed ? ".enc.z" : "");
private = kzalloc(sizeof(*private), GFP_KERNEL);
if (!private)
goto fail_inode;
dentry = d_alloc_name(root, name);
if (!dentry)
goto fail_private;
private->record = record;
inode->i_size = private->total_size = size;
inode->i_private = private;
if (record->time.tv_sec)
@ -349,7 +348,7 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
fail_private:
free_pstore_private(private);
fail_alloc:
fail_inode:
iput(inode);
fail: