[PULL 08/10] migration/multifd: Replace assert() with error_setg() in recv paths

[Peter Xu <peterx@redhat.com>]

QPL and UADK multifd backends use assert() to validate wire-controlled
fields like per-page compressed lengths and packet size consistency.  These
asserts will stop working with -DNDEBUG builds, so may stop working.

Replace all assert() calls in the receive path with proper error_setg() so
validation failures are reported gracefully rather than crashing or
silently ignored.

While at it, touch up an assert() in qatzip recv path too.

Cc: qemu-stable <qemu-stable@nongnu.org>
Cc: Yuan Liu <yuan1.liu@intel.com>
Cc: Yichen Wang <yichen.wang@bytedance.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20260728210417.1925078-4-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/multifd-qatzip.c |  5 ++++-
 migration/multifd-qpl.c    | 24 ++++++++++++++++++++----
 migration/multifd-uadk.c   | 24 ++++++++++++++++++++----
 3 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/migration/multifd-qatzip.c b/migration/multifd-qatzip.c
index 7419e5dc0d..0262e81eac 100644
--- a/migration/multifd-qatzip.c
+++ b/migration/multifd-qatzip.c
@@ -348,7 +348,10 @@ static int qatzip_recv(MultiFDRecvParams *p, Error **errp)
 
     multifd_recv_zero_page_process(p);
     if (!p->normal_num) {
-        assert(in_size == 0);
+        if (in_size != 0) {
+            error_setg(errp, "multifd %u: expected empty packet", p->id);
+            return -1;
+        }
         return 0;
     }
 
diff --git a/migration/multifd-qpl.c b/migration/multifd-qpl.c
index 52902eb00c..3826e7f340 100644
--- a/migration/multifd-qpl.c
+++ b/migration/multifd-qpl.c
@@ -664,26 +664,42 @@ static int multifd_qpl_recv(MultiFDRecvParams *p, Error **errp)
     }
     multifd_recv_zero_page_process(p);
     if (!p->normal_num) {
-        assert(in_size == 0);
+        if (in_size != 0) {
+            error_setg(errp, "multifd %u: expected empty packet", p->id);
+            return -1;
+        }
         return 0;
     }
 
     /* read compressed page lengths */
     len = p->normal_num * sizeof(uint32_t);
-    assert(len < in_size);
+    if (len >= in_size) {
+        error_setg(errp, "multifd %u: header len %"PRIu32
+                   " >= packet size %"PRIu32, p->id, len, in_size);
+        return -1;
+    }
     ret = qio_channel_read_all(p->c, (void *) qpl->zlen, len, errp);
     if (ret != 0) {
         return ret;
     }
     for (int i = 0; i < p->normal_num; i++) {
         qpl->zlen[i] = be32_to_cpu(qpl->zlen[i]);
-        assert(qpl->zlen[i] <= multifd_ram_page_size());
+        if (qpl->zlen[i] > multifd_ram_page_size()) {
+            error_setg(errp, "multifd %u: page %d compressed len %"
+                       PRIu32" too large", p->id, i, qpl->zlen[i]);
+            return -1;
+        }
         zbuf_len += qpl->zlen[i];
         ramblock_recv_bitmap_set_offset(p->block, p->normal[i]);
     }
 
     /* read compressed pages */
-    assert(in_size == len + zbuf_len);
+    if (in_size != len + zbuf_len) {
+        error_setg(errp, "multifd %u: packet size %"PRIu32
+                   " != header %"PRIu32" + data %"PRIu32,
+                   p->id, in_size, len, zbuf_len);
+        return -1;
+    }
     ret = qio_channel_read_all(p->c, (void *) qpl->zbuf, zbuf_len, errp);
     if (ret != 0) {
         return ret;
diff --git a/migration/multifd-uadk.c b/migration/multifd-uadk.c
index fd7cd9b5e8..d373615ba8 100644
--- a/migration/multifd-uadk.c
+++ b/migration/multifd-uadk.c
@@ -245,12 +245,19 @@ static int multifd_uadk_recv(MultiFDRecvParams *p, Error **errp)
 
     multifd_recv_zero_page_process(p);
     if (!p->normal_num) {
-        assert(in_size == 0);
+        if (in_size != 0) {
+            error_setg(errp, "multifd %u: expected empty packet", p->id);
+            return -1;
+        }
         return 0;
     }
 
     /* read compressed data lengths */
-    assert(hdr_len < in_size);
+    if (hdr_len >= in_size) {
+        error_setg(errp, "multifd %u: header len %"PRIu32
+                   " >= packet size %"PRIu32, p->id, hdr_len, in_size);
+        return -1;
+    }
     ret = qio_channel_read_all(p->c, (void *) uadk_data->buf_hdr,
                                hdr_len, errp);
     if (ret != 0) {
@@ -259,12 +266,21 @@ static int multifd_uadk_recv(MultiFDRecvParams *p, Error **errp)
 
     for (int i = 0; i < p->normal_num; i++) {
         uadk_data->buf_hdr[i] = be32_to_cpu(uadk_data->buf_hdr[i]);
+        if (uadk_data->buf_hdr[i] > page_size) {
+            error_setg(errp, "multifd %u: page %d compressed len %"PRIu32
+                       " too large", p->id, i, uadk_data->buf_hdr[i]);
+            return -1;
+        }
         data_len += uadk_data->buf_hdr[i];
-        assert(uadk_data->buf_hdr[i] <= page_size);
     }
 
     /* read compressed data */
-    assert(in_size == hdr_len + data_len);
+    if (in_size != hdr_len + data_len) {
+        error_setg(errp, "multifd %u: packet size %"PRIu32
+                   " != header %"PRIu32" + data %"PRIu32,
+                   p->id, in_size, hdr_len, data_len);
+        return -1;
+    }
     ret = qio_channel_read_all(p->c, (void *)buf, data_len, errp);
     if (ret != 0) {
         return ret;
-- 
2.54.0