Messages in this thread Patch in this message | | | From | Rustam Subkhankulov <> | Subject | [PATCH v2] fs/inode.c: change the order of initialization in inode_init_always() | Date | Mon, 29 Aug 2022 22:25:21 +0300 |
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If function security_inode_alloc() returns a nonzero value due to an error (e.g. fail to allocate memory), then some of the fields, including 'i_private', will not be initialized.
After that, if the fs-specfic free_inode function is called in i_callback(), the nonzero value of 'i_private' field can be interpreted as initialized. As a result, this can cause dereferencing of random value pointer (e.g. nilfs2).
In earlier versions, a similar situation could occur with the 'u' union in 'inode' structure.
Found by Linux Verification Center (linuxtesting.org) with syzkaller.
Signed-off-by: Rustam Subkhankulov <subkhankulov@ispras.ru> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") --- fs/inode.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/fs/inode.c b/fs/inode.c index ba1de23c13c1..a2892d85993d 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -192,8 +192,6 @@ int inode_init_always(struct super_block *sb, struct inode *inode) inode->i_wb_frn_history = 0; #endif - if (security_inode_alloc(inode)) - goto out; spin_lock_init(&inode->i_lock); lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key); @@ -228,6 +226,10 @@ int inode_init_always(struct super_block *sb, struct inode *inode) inode->i_fsnotify_mask = 0; #endif inode->i_flctx = NULL; + + if (security_inode_alloc(inode)) + goto out; + this_cpu_inc(nr_inodes); return 0; -- 2.34.1
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