The function qemu_strtoul() reads 'unsigned long' sized data, which is larger than uint32_t on 64-bit machines.
Even though the snap_id field in the header is 32-bits, we must accomodate the full size in qemu_strtoul(). This patch also adds more meaningful error handling to the qemu_strtoul() call, and subsequent results. Reported-by: Paolo Bonzini <pbonz...@redhat.com> Signed-off-by: Jeff Cody <jc...@redhat.com> --- block/sheepdog.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/block/sheepdog.c b/block/sheepdog.c index 8739acc..418f6ba 100644 --- a/block/sheepdog.c +++ b/block/sheepdog.c @@ -2543,7 +2543,7 @@ static int sd_snapshot_delete(BlockDriverState *bs, const char *name, Error **errp) { - uint32_t snap_id = 0; + unsigned long snap_id = 0; char snap_tag[SD_MAX_VDI_TAG_LEN]; Error *local_err = NULL; int fd, ret; @@ -2565,12 +2565,22 @@ static int sd_snapshot_delete(BlockDriverState *bs, memset(buf, 0, sizeof(buf)); memset(snap_tag, 0, sizeof(snap_tag)); pstrcpy(buf, SD_MAX_VDI_LEN, s->name); - if (qemu_strtoul(snapshot_id, NULL, 10, (unsigned long *)&snap_id)) { - return -1; + ret = qemu_strtoul(snapshot_id, NULL, 10, &snap_id); + if (ret) { + error_setg_errno(errp, -ret, "Invalid snapshot ID: %s", + snapshot_id ? snapshot_id : "<null>"); + return ret; + } + + if (snap_id > UINT32_MAX) { + error_setg_errno(errp, EINVAL, "Snapshot ID numeric value %" PRId64 + " exceeds Sheepdog maximum of %" PRId32, snap_id, + UINT32_MAX); + return -EINVAL; } if (snap_id) { - hdr.snapid = snap_id; + hdr.snapid = (uint32_t) snap_id; } else { pstrcpy(snap_tag, sizeof(snap_tag), snapshot_id); pstrcpy(buf + SD_MAX_VDI_LEN, SD_MAX_VDI_TAG_LEN, snap_tag); -- 1.9.3