On 8/15/22 11:08 PM, Dongliang Mu wrote: > From: Dongliang Mu <mudongliangabcd@xxxxxxxxx> > > In alloc_inode, inode_init_always() could return -ENOMEM if > security_inode_alloc() fails, which causes inode->i_private > uninitialized. Then nilfs_is_metadata_file_inode() returns > true and nilfs_free_inode() wrongly calls nilfs_mdt_destroy(), > which frees the uninitialized inode->i_private > and leads to crashes(e.g., UAF/GPF). > > Fix this by moving security_inode_alloc just prior to > this_cpu_inc(nr_inodes) > > Link: https://lkml.kernel.org/r/CAFcO6XOcf1Jj2SeGt=jJV59wmhESeSKpfR0omdFRq+J9nD1vfQ@xxxxxxxxxxxxxx > Reported-by: butt3rflyh4ck <butterflyhuangxx@xxxxxxxxx> > Reported-by: Hao Sun <sunhao.th@xxxxxxxxx> > Reported-by: Jiacheng Xu <stitch@xxxxxxxxxx> > Signed-off-by: Dongliang Mu <mudongliangabcd@xxxxxxxxx> > Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > --- > v1->v2: move security_inode_alloc at the very end according to Al Viro > other than initializing i_private before security_inode_alloc. > fs/inode.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/fs/inode.c b/fs/inode.c > index 6462276dfdf0..49d1eb91728c 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 +226,9 @@ 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; Seems like the out: label could be removed, and simply return -ENOMEM directly here, but that's just a nitpick. -Eric > this_cpu_inc(nr_inodes); > > return 0;
