Re: [syzbot] [jfs?] KASAN: slab-use-after-free Read in lbmIODone

[Edward Adam Davis]

#syz test: upstream master

diff --git a/fs/jfs/jfs_logmgr.c b/fs/jfs/jfs_logmgr.c
index ada00d5bc214..729baf49a048 100644
--- a/fs/jfs/jfs_logmgr.c
+++ b/fs/jfs/jfs_logmgr.c
@@ -1986,7 +1986,7 @@ static int lbmRead(struct jfs_log * log, int pn, struct lbuf ** bpp)
 		submit_bio(bio);
 	}
 
-	wait_event(bp->l_ioevent, (bp->l_flag != lbmREAD));
+	wait_event(bp->l_ioevent, (bp->l_flag & lbmDONE));
 
 	return 0;
 }
@@ -2180,7 +2180,6 @@ static void lbmIODone(struct bio *bio)
 
 	LCACHE_LOCK(flags);		/* disable+lock */
 
-	bp->l_flag |= lbmDONE;
 
 	if (bio->bi_status) {
 		bp->l_flag |= lbmERROR;
@@ -2196,12 +2195,7 @@ static void lbmIODone(struct bio *bio)
 	if (bp->l_flag & lbmREAD) {
 		bp->l_flag &= ~lbmREAD;
 
-		LCACHE_UNLOCK(flags);	/* unlock+enable */
-
-		/* wakeup I/O initiator */
-		LCACHE_WAKEUP(&bp->l_ioevent);
-
-		return;
+		goto out;
 	}
 
 	/*
@@ -2224,9 +2218,7 @@ static void lbmIODone(struct bio *bio)
 	log->clsn = (bp->l_pn << L2LOGPSIZE) + bp->l_ceor;
 
 	if (bp->l_flag & lbmDIRECT) {
-		LCACHE_WAKEUP(&bp->l_ioevent);
-		LCACHE_UNLOCK(flags);
-		return;
+		goto out;
 	}
 
 	tail = log->wqueue;
@@ -2278,10 +2270,7 @@ static void lbmIODone(struct bio *bio)
 	 * leave buffer for i/o initiator to dispose
 	 */
 	if (bp->l_flag & lbmSYNC) {
-		LCACHE_UNLOCK(flags);	/* unlock+enable */
-
-		/* wakeup I/O initiator */
-		LCACHE_WAKEUP(&bp->l_ioevent);
+		goto out;
 	}
 
 	/*
@@ -2290,6 +2279,7 @@ static void lbmIODone(struct bio *bio)
 	else if (bp->l_flag & lbmGC) {
 		LCACHE_UNLOCK(flags);
 		lmPostGC(bp);
+		LCACHE_LOCK(flags);		/* disable+lock */
 	}
 
 	/*
@@ -2302,9 +2292,12 @@ static void lbmIODone(struct bio *bio)
 		assert(bp->l_flag & lbmRELEASE);
 		assert(bp->l_flag & lbmFREE);
 		lbmfree(bp);
-
-		LCACHE_UNLOCK(flags);	/* unlock+enable */
 	}
+out:
+	bp->l_flag |= lbmDONE;
+	/* wakeup I/O initiator */
+	LCACHE_WAKEUP(&bp->l_ioevent);
+	LCACHE_UNLOCK(flags);	/* unlock+enable */
 }
 
 int jfsIOWait(void *arg)