[PATCH 09/16] hw/block/nvme: refactor request bounds checking

[Klaus Jensen]

From: Klaus Jensen <k.jensen@samsung.com>

Hoist bounds checking into its own function and check for wrap-around.

Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
---
 hw/block/nvme.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index 530f5155eac0..35bc1a7b7e21 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -553,6 +553,18 @@ static void nvme_clear_events(NvmeCtrl *n, uint8_t 
event_type)
     }
 }
 
+static inline uint16_t nvme_check_bounds(NvmeCtrl *n, NvmeNamespace *ns,
+                                         uint64_t slba, uint32_t nlb)
+{
+    uint64_t nsze = le64_to_cpu(ns->id_ns.nsze);
+
+    if (unlikely(UINT64_MAX - slba < nlb || slba + nlb > nsze)) {
+        return NVME_LBA_RANGE | NVME_DNR;
+    }
+
+    return NVME_SUCCESS;
+}
+
 static void nvme_rw_cb(void *opaque, int ret)
 {
     NvmeRequest *req = opaque;
@@ -600,12 +612,14 @@ static uint16_t nvme_write_zeros(NvmeCtrl *n, 
NvmeNamespace *ns, NvmeCmd *cmd,
     uint32_t nlb  = le16_to_cpu(rw->nlb) + 1;
     uint64_t offset = slba << data_shift;
     uint32_t count = nlb << data_shift;
+    uint16_t status;
 
     trace_pci_nvme_write_zeroes(nvme_cid(req), slba, nlb);
 
-    if (unlikely(slba + nlb > ns->id_ns.nsze)) {
+    status = nvme_check_bounds(n, ns, slba, nlb);
+    if (status) {
         trace_pci_nvme_err_invalid_lba_range(slba, nlb, ns->id_ns.nsze);
-        return NVME_LBA_RANGE | NVME_DNR;
+        return status;
     }
 
     block_acct_start(blk_get_stats(n->conf.blk), &req->acct, 0,
@@ -628,13 +642,15 @@ static uint16_t nvme_rw(NvmeCtrl *n, NvmeNamespace *ns, 
NvmeCmd *cmd,
     uint64_t data_offset = slba << data_shift;
     int is_write = rw->opcode == NVME_CMD_WRITE ? 1 : 0;
     enum BlockAcctType acct = is_write ? BLOCK_ACCT_WRITE : BLOCK_ACCT_READ;
+    uint16_t status;
 
     trace_pci_nvme_rw(is_write ? "write" : "read", nlb, data_size, slba);
 
-    if (unlikely((slba + nlb) > ns->id_ns.nsze)) {
-        block_acct_invalid(blk_get_stats(n->conf.blk), acct);
+    status = nvme_check_bounds(n, ns, slba, nlb);
+    if (status) {
         trace_pci_nvme_err_invalid_lba_range(slba, nlb, ns->id_ns.nsze);
-        return NVME_LBA_RANGE | NVME_DNR;
+        block_acct_invalid(blk_get_stats(n->conf.blk), acct);
+        return status;
     }
 
     if (nvme_map(n, cmd, data_size, req)) {
-- 
2.27.0