From 90aa83c6bdaa6ea82e1af5a02f77ff80088653d0 Mon Sep 17 00:00:00 2001
From: mtmcp <141645996+mtmcp@users.noreply.github.com>
Date: Tue, 31 Mar 2026 07:04:42 -0300
Subject: [PATCH] common: add bounds check in common_init_result::sampler to
 prevent segfault on failed model load (#21082)

* common: add bounds check in common_init_result::sampler to prevent segfault on failed model load

* Revert a308e584cae3fa8cee1d739a858a2d780f1de009

* Add regression test

* Remove regression test for init-fail sampler check
---
 common/common.cpp               | 3 +++
 tools/completion/completion.cpp | 8 +-------
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/common/common.cpp b/common/common.cpp
index a9bd494191..497cfaad5e 100644
--- a/common/common.cpp
+++ b/common/common.cpp
@@ -1243,6 +1243,9 @@ llama_context * common_init_result::context() {
 }
 
 common_sampler * common_init_result::sampler(llama_seq_id seq_id) {
+    if (seq_id < 0 || seq_id >= (int) pimpl->samplers.size()) {
+        return nullptr;
+    }
     return pimpl->samplers[seq_id].get();
 }
 
diff --git a/tools/completion/completion.cpp b/tools/completion/completion.cpp
index 716a30fe9a..813526a0ec 100644
--- a/tools/completion/completion.cpp
+++ b/tools/completion/completion.cpp
@@ -146,19 +146,13 @@ int main(int argc, char ** argv) {
 
     ctx   = llama_init->context();
     model = llama_init->model();
+    smpl  = llama_init->sampler(0);
 
     if (ctx == NULL) {
         LOG_ERR("%s: error: unable to create context\n", __func__);
         return 1;
     }
 
-    if (model == NULL) {
-        LOG_ERR("%s: error: unable to load model\n", __func__);
-        return 1;
-    }
-
-    smpl = llama_init->sampler(0);
-
     llama_memory_t mem = llama_get_memory(ctx);
     const llama_vocab * vocab = llama_model_get_vocab(model);