jfs: UBSAN: shift-out-of-bounds in dbFindBits

rbrasga · kleikamp · commit b0b2fc815e51 · 2024-08-23T13:14:28.000-05:00
Fix issue with UBSAN throwing shift-out-of-bounds warning.

Reported-by: syzbot+e38d703eeb410b17b473@syzkaller.appspotmail.com
Signed-off-by: Remington Brasga &lt;rbrasga@uci.edu&gt;
Signed-off-by: Dave Kleikamp &lt;dave.kleikamp@oracle.com&gt;
diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
@@ -3022,7 +3022,7 @@ static int dbFindBits(u32 word, int l2nb)
 
 	/* scan the word for nb free bits at nb alignments.
 	 */
-	for (bitno = 0; mask != 0; bitno += nb, mask >>= nb) {
+	for (bitno = 0; mask != 0; bitno += nb, mask = (mask >> nb)) {
 		if ((mask & word) == mask)
 			break;
 	}

Original file line number	Diff line number	Diff line change
`@@ -3022,7 +3022,7 @@ static int dbFindBits(u32 word, int l2nb)`
`3022`	`3022`
`3023`	`3023`	`/* scan the word for nb free bits at nb alignments.`
`3024`	`3024`	`*/`
`3025`		`- for (bitno = 0; mask != 0; bitno += nb, mask >>= nb) {`
	`3025`	`+ for (bitno = 0; mask != 0; bitno += nb, mask = (mask >> nb)) {`
`3026`	`3026`	`if ((mask & word) == mask)`
`3027`	`3027`	`break;`
`3028`	`3028`	`}`