FreeBSD: Fix translation from ABD to physical pages

In hypothetical case of non-linear ABD with single segment, multiple to page size but not aligned to it, vdev_geom_fill_unmap_cb() could fill one page less into bio_ma array. I am not sure it is exploitable, but better to be safe than sorry. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Reported-by: Mark Johnston <[email protected]> Signed-off-by: Alexander Motin <[email protected]> Closes openzfs#13345
andrewc12 · Sep 23, 2022 · a56d611 · a56d611
1 parent c977cda
commit a56d611
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/module/os/freebsd/zfs/vdev_geom.c b/module/os/freebsd/zfs/vdev_geom.c
@@ -1131,8 +1131,12 @@ vdev_geom_fill_unmap_cb(void *buf, size_t len, void *priv)
 	vm_offset_t addr = (vm_offset_t)buf;
 	vm_offset_t end = addr + len;
 
-	if (bp->bio_ma_n == 0)
+	if (bp->bio_ma_n == 0) {
 		bp->bio_ma_offset = addr & PAGE_MASK;
+		addr &= ~PAGE_MASK;
+	} else {
+		ASSERT0(P2PHASE(addr, PAGE_SIZE));
+	}
 	do {
 		bp->bio_ma[bp->bio_ma_n++] =
 		    PHYS_TO_VM_PAGE(pmap_kextract(addr));