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fanotify: update connector fsid cache on add mark 

When implementing connector fsid cache, we only initialized the cache
when the first mark added to object was added by FAN_REPORT_FID group.
We forgot to update conn->fsid when the second mark is added by
FAN_REPORT_FID group to an already attached connector without fsid
cache.

Reported-and-tested-by: syzbot+c277e8e2f46414645508@syzkaller.appspotmail.com
Fixes: 77115225ac ("fanotify: cache fsid in fsnotify_mark_connector")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Amir Goldstein 2019-06-19 13:34:44 +03:00 committed by Jan Kara
parent c6d9c35d16
commit c285a2f01d
3 changed files with 18 additions and 4 deletions
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4
fs/notify/fanotify/fanotify.c
View File

@ -355,6 +355,10 @@ static __kernel_fsid_t fanotify_get_fsid(struct fsnotify_iter_info *iter_info)
/* Mark is just getting destroyed or created? */
if (!conn)
continue;
if (!(conn->flags & FSNOTIFY_CONN_FLAG_HAS_FSID))
continue;
/* Pairs with smp_wmb() in fsnotify_add_mark_list() */
smp_rmb();
fsid = conn->fsid;
if (WARN_ON_ONCE(!fsid.val[0] && !fsid.val[1]))
continue;

14
fs/notify/mark.c
View File

@ -482,10 +482,13 @@ static int fsnotify_attach_connector_to_object(fsnotify_connp_t *connp,
conn->type = type;
conn->obj = connp;
/* Cache fsid of filesystem containing the object */
if (fsid)
if (fsid) {
conn->fsid = *fsid;
else
conn->flags = FSNOTIFY_CONN_FLAG_HAS_FSID;
} else {
conn->fsid.val[0] = conn->fsid.val[1] = 0;
conn->flags = 0;
}
if (conn->type == FSNOTIFY_OBJ_TYPE_INODE)
inode = igrab(fsnotify_conn_inode(conn));
/*
@ -560,7 +563,12 @@ restart:
if (err)
return err;
goto restart;
} else if (fsid && (conn->fsid.val[0] || conn->fsid.val[1]) &&
} else if (fsid && !(conn->flags & FSNOTIFY_CONN_FLAG_HAS_FSID)) {
conn->fsid = *fsid;
/* Pairs with smp_rmb() in fanotify_get_fsid() */
smp_wmb();
conn->flags |= FSNOTIFY_CONN_FLAG_HAS_FSID;
} else if (fsid && (conn->flags & FSNOTIFY_CONN_FLAG_HAS_FSID) &&
(fsid->val[0] != conn->fsid.val[0] ||
fsid->val[1] != conn->fsid.val[1])) {
/*

4
include/linux/fsnotify_backend.h
View File

@ -292,7 +292,9 @@ typedef struct fsnotify_mark_connector __rcu *fsnotify_connp_t;
*/
struct fsnotify_mark_connector {
spinlock_t lock;
unsigned int type; /* Type of object [lock] */
unsigned short type; /* Type of object [lock] */
#define FSNOTIFY_CONN_FLAG_HAS_FSID 0x01
unsigned short flags; /* flags [lock] */
__kernel_fsid_t fsid; /* fsid of filesystem containing object */
union {
/* Object pointer [lock] */