On Tue 16-04-24 21:14:52, Amir Goldstein wrote: > Protect against use after free when filesystem calls fsnotify_sb_error() > during fs shutdown. > > Move freeing of sb->s_fsnotify_info to destroy_super_work(), because it > may be accessed from fs shutdown context. > > Reported-by: syzbot+5e3f9b2a67b45f16d4e6@xxxxxxxxxxxxxxxxxxxxxxxxx > Suggested-by: Jan Kara <jack@xxxxxxx> > Link: https://lore.kernel.org/linux-fsdevel/20240416173211.4lnmgctyo4jn5fha@quack3/ > Fixes: 07a3b8d0bf72 ("fsnotify: lazy attach fsnotify_sb_info state to sb") > Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx> Thanks! Added to my tree. Honza > --- > fs/notify/fsnotify.c | 6 +++++- > fs/super.c | 1 + > include/linux/fsnotify_backend.h | 4 ++++ > 3 files changed, 10 insertions(+), 1 deletion(-) > > diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c > index 2ae965ef37e8..ff69ae24c4e8 100644 > --- a/fs/notify/fsnotify.c > +++ b/fs/notify/fsnotify.c > @@ -103,7 +103,11 @@ void fsnotify_sb_delete(struct super_block *sb) > WARN_ON(fsnotify_sb_has_priority_watchers(sb, FSNOTIFY_PRIO_CONTENT)); > WARN_ON(fsnotify_sb_has_priority_watchers(sb, > FSNOTIFY_PRIO_PRE_CONTENT)); > - kfree(sbinfo); > +} > + > +void fsnotify_sb_free(struct super_block *sb) > +{ > + kfree(sb->s_fsnotify_info); > } > > /* > diff --git a/fs/super.c b/fs/super.c > index 69ce6c600968..b72f1d288e95 100644 > --- a/fs/super.c > +++ b/fs/super.c > @@ -274,6 +274,7 @@ static void destroy_super_work(struct work_struct *work) > { > struct super_block *s = container_of(work, struct super_block, > destroy_work); > + fsnotify_sb_free(s); > security_sb_free(s); > put_user_ns(s->s_user_ns); > kfree(s->s_subtype); > diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h > index 7f1ab8264e41..4dd6143db271 100644 > --- a/include/linux/fsnotify_backend.h > +++ b/include/linux/fsnotify_backend.h > @@ -576,6 +576,7 @@ extern int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data > extern void __fsnotify_inode_delete(struct inode *inode); > extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt); > extern void fsnotify_sb_delete(struct super_block *sb); > +extern void fsnotify_sb_free(struct super_block *sb); > extern u32 fsnotify_get_cookie(void); > > static inline __u32 fsnotify_parent_needed_mask(__u32 mask) > @@ -880,6 +881,9 @@ static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt) > static inline void fsnotify_sb_delete(struct super_block *sb) > {} > > +static inline void fsnotify_sb_free(struct super_block *sb) > +{} > + > static inline void fsnotify_update_flags(struct dentry *dentry) > {} > > -- > 2.34.1 > -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
