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3eaa22d688
commitec306600d5upstream. is_open, has_lease and on_list are stored in the same bitfield byte in struct cached_fid but are updated in different code paths that may run concurrently. Bitfield assignments generate byte read–modify–write operations (e.g. `orb $mask, addr` on x86_64), so updating one flag can restore stale values of the others. A possible interleaving is: CPU1: load old byte (has_lease=1, on_list=1) CPU2: clear both flags (store 0) CPU1: RMW store (old | IS_OPEN) -> reintroduces cleared bits To avoid this class of races, convert these flags to separate bool fields. Cc: stable@vger.kernel.org Fixes:ebe98f1447("cifs: enable caching of directories for which a lease is held") Signed-off-by: Henrique Carvalho <henrique.carvalho@suse.com> Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
86 lines
2.2 KiB
C
86 lines
2.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Functions to handle the cached directory entries
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*
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* Copyright (c) 2022, Ronnie Sahlberg <lsahlber@redhat.com>
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*/
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#ifndef _CACHED_DIR_H
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#define _CACHED_DIR_H
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struct cached_dirent {
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struct list_head entry;
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char *name;
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int namelen;
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loff_t pos;
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struct cifs_fattr fattr;
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};
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struct cached_dirents {
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bool is_valid:1;
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bool is_failed:1;
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struct file *file; /*
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* Used to associate the cache with a single
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* open file instance.
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*/
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struct mutex de_mutex;
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int pos; /* Expected ctx->pos */
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struct list_head entries;
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};
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struct cached_fid {
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struct list_head entry;
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struct cached_fids *cfids;
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const char *path;
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bool has_lease;
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bool is_open;
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bool on_list;
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bool file_all_info_is_valid;
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unsigned long time; /* jiffies of when lease was taken */
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struct kref refcount;
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struct cifs_fid fid;
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spinlock_t fid_lock;
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struct cifs_tcon *tcon;
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struct dentry *dentry;
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struct work_struct put_work;
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struct work_struct close_work;
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struct smb2_file_all_info file_all_info;
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struct cached_dirents dirents;
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};
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/* default MAX_CACHED_FIDS is 16 */
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struct cached_fids {
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/* Must be held when:
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* - accessing the cfids->entries list
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* - accessing the cfids->dying list
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*/
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spinlock_t cfid_list_lock;
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int num_entries;
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struct list_head entries;
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struct list_head dying;
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struct work_struct invalidation_work;
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struct delayed_work laundromat_work;
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};
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extern struct cached_fids *init_cached_dirs(void);
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extern void free_cached_dirs(struct cached_fids *cfids);
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extern int open_cached_dir(unsigned int xid, struct cifs_tcon *tcon,
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const char *path,
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struct cifs_sb_info *cifs_sb,
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bool lookup_only, struct cached_fid **cfid);
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extern int open_cached_dir_by_dentry(struct cifs_tcon *tcon,
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struct dentry *dentry,
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struct cached_fid **cfid);
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extern void close_cached_dir(struct cached_fid *cfid);
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extern void drop_cached_dir_by_name(const unsigned int xid,
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struct cifs_tcon *tcon,
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const char *name,
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struct cifs_sb_info *cifs_sb);
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extern void close_all_cached_dirs(struct cifs_sb_info *cifs_sb);
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extern void invalidate_all_cached_dirs(struct cifs_tcon *tcon);
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extern int cached_dir_lease_break(struct cifs_tcon *tcon, __u8 lease_key[16]);
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#endif /* _CACHED_DIR_H */
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