Commit 4c6d80e1 authored Jul 05, 2019 by Norbert Manthey Committed by Kees Cook Jul 08, 2019

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: 83f70f07 ("pstore: Do not duplicate record metadata")
Fixes: 1dfff7dd ("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>

parent fa1af758

fs/pstore/inode.c

+6 −7

Original line number	Diff line number	Diff line
		@@ -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:

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