From ecfb0b5f42c3662e36d5cd444c0aa2ebc8501589 Mon Sep 17 00:00:00 2001 From: tuxoko Date: Sun, 26 Apr 2015 16:09:41 +0800 Subject: [PATCH] Fix misuse of input argument in traverse_visitbp In traverse_visitbp(), the input argument dnp is modified in the middle to point to a temporary buffer. Originally this doesn't matter, because no user of TRAVERSE_POST dereferences it. However, in fbeddd6 a piece of code is added dereferencing dnp after the modification, creating a possible bug. We fix this by creating a new local variable cdnp for the DMU_OT_DNODE case, so we don't modify the input argument. Also we introduce different local variables in the DMU_OT_OBJSET case to prevent confusion between the input argument. Signed-off-by: Chunwei Chen Signed-off-by: Richard Yao Signed-off-by: Tim Chase Signed-off-by: Brian Behlendorf Closes #2060 --- module/zfs/dmu_traverse.c | 32 +++++++++++++++++--------------- 1 file changed, 17 insertions(+), 15 deletions(-) diff --git a/module/zfs/dmu_traverse.c b/module/zfs/dmu_traverse.c index 9280a89b2f85..3f98c8feb974 100644 --- a/module/zfs/dmu_traverse.c +++ b/module/zfs/dmu_traverse.c @@ -314,21 +314,22 @@ traverse_visitbp(traverse_data_t *td, const dnode_phys_t *dnp, uint32_t flags = ARC_WAIT; int32_t i; int32_t epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT; + dnode_phys_t *cdnp; err = arc_read(NULL, td->td_spa, bp, arc_getbuf_func, &buf, ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb); if (err != 0) goto post; - dnp = buf->b_data; + cdnp = buf->b_data; for (i = 0; i < epb; i++) { - prefetch_dnode_metadata(td, &dnp[i], zb->zb_objset, + prefetch_dnode_metadata(td, &cdnp[i], zb->zb_objset, zb->zb_blkid * epb + i); } /* recursively visitbp() blocks below this */ for (i = 0; i < epb; i++) { - err = traverse_dnode(td, &dnp[i], zb->zb_objset, + err = traverse_dnode(td, &cdnp[i], zb->zb_objset, zb->zb_blkid * epb + i); if (err != 0) break; @@ -336,7 +337,7 @@ traverse_visitbp(traverse_data_t *td, const dnode_phys_t *dnp, } else if (BP_GET_TYPE(bp) == DMU_OT_OBJSET) { uint32_t flags = ARC_WAIT; objset_phys_t *osp; - dnode_phys_t *dnp; + dnode_phys_t *mdnp, *gdnp, *udnp; err = arc_read(NULL, td->td_spa, bp, arc_getbuf_func, &buf, ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb); @@ -344,26 +345,27 @@ traverse_visitbp(traverse_data_t *td, const dnode_phys_t *dnp, goto post; osp = buf->b_data; - dnp = &osp->os_meta_dnode; - prefetch_dnode_metadata(td, dnp, zb->zb_objset, + mdnp = &osp->os_meta_dnode; + gdnp = &osp->os_groupused_dnode; + udnp = &osp->os_userused_dnode; + + prefetch_dnode_metadata(td, mdnp, zb->zb_objset, DMU_META_DNODE_OBJECT); if (arc_buf_size(buf) >= sizeof (objset_phys_t)) { - prefetch_dnode_metadata(td, &osp->os_groupused_dnode, - zb->zb_objset, DMU_GROUPUSED_OBJECT); - prefetch_dnode_metadata(td, &osp->os_userused_dnode, - zb->zb_objset, DMU_USERUSED_OBJECT); + prefetch_dnode_metadata(td, gdnp, zb->zb_objset, + DMU_GROUPUSED_OBJECT); + prefetch_dnode_metadata(td, udnp, zb->zb_objset, + DMU_USERUSED_OBJECT); } - err = traverse_dnode(td, dnp, zb->zb_objset, + err = traverse_dnode(td, mdnp, zb->zb_objset, DMU_META_DNODE_OBJECT); if (err == 0 && arc_buf_size(buf) >= sizeof (objset_phys_t)) { - dnp = &osp->os_groupused_dnode; - err = traverse_dnode(td, dnp, zb->zb_objset, + err = traverse_dnode(td, gdnp, zb->zb_objset, DMU_GROUPUSED_OBJECT); } if (err == 0 && arc_buf_size(buf) >= sizeof (objset_phys_t)) { - dnp = &osp->os_userused_dnode; - err = traverse_dnode(td, dnp, zb->zb_objset, + err = traverse_dnode(td, udnp, zb->zb_objset, DMU_USERUSED_OBJECT); } }