The nwnames field in TWALK message is assumed to be >=0 and <= MAXWELEM which is defined as macro P9_MAXWELEM (16) in virtio-9p.h as per 9p2000 RFC. Appropriate changes are required in V9fsWalkState and v9fs_walk.
v2: - Added check in v9fs_walk_complete as well. Signed-off-by: Harsh Prateek Bora <ha...@linux.vnet.ibm.com> --- hw/9pfs/virtio-9p.c | 7 +++++-- hw/9pfs/virtio-9p.h | 2 +- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c index 9b44bd0..dde51bc 100644 --- a/hw/9pfs/virtio-9p.c +++ b/hw/9pfs/virtio-9p.c @@ -1708,7 +1708,7 @@ static void v9fs_walk_complete(V9fsState *s, V9fsWalkState *vs, int err) { complete_pdu(s, vs->pdu, err); - if (vs->nwnames) { + if (vs->nwnames <= P9_MAXWELEM) { for (vs->name_idx = 0; vs->name_idx < vs->nwnames; vs->name_idx++) { v9fs_string_free(&vs->wnames[vs->name_idx]); } @@ -1805,7 +1805,7 @@ static void v9fs_walk(V9fsState *s, V9fsPDU *pdu) vs->offset += pdu_unmarshal(vs->pdu, vs->offset, "ddw", &fid, &newfid, &vs->nwnames); - if (vs->nwnames) { + if (vs->nwnames <= P9_MAXWELEM) { vs->wnames = qemu_mallocz(sizeof(vs->wnames[0]) * vs->nwnames); vs->qids = qemu_mallocz(sizeof(vs->qids[0]) * vs->nwnames); @@ -1814,6 +1814,9 @@ static void v9fs_walk(V9fsState *s, V9fsPDU *pdu) vs->offset += pdu_unmarshal(vs->pdu, vs->offset, "s", &vs->wnames[i]); } + } else { + err = -EINVAL; + goto out; } vs->fidp = lookup_fid(s, fid); diff --git a/hw/9pfs/virtio-9p.h b/hw/9pfs/virtio-9p.h index e7d2326..119b12c 100644 --- a/hw/9pfs/virtio-9p.h +++ b/hw/9pfs/virtio-9p.h @@ -307,7 +307,7 @@ typedef struct V9fsStatStateDotl { typedef struct V9fsWalkState { V9fsPDU *pdu; size_t offset; - int16_t nwnames; + uint16_t nwnames; int name_idx; V9fsQID *qids; V9fsFidState *fidp; -- 1.7.1.1