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Thu, 19 Mar 2026 13:26:13 -0700 (PDT) Received: from LQ5W56KC4T ([2001:8a0:672f:7800:e0e1:55cd:f0b:b1e5]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43b644ae16fsm1347544f8f.8.2026.03.19.13.26.12 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 19 Mar 2026 13:26:13 -0700 (PDT) From: Eric Curtin X-Google-Original-From: Eric Curtin To: linux-hyperv@vger.kernel.org Cc: linux-kernel@vger.kernel.org, iourit@linux.microsoft.com, wei.liu@kernel.org, decui@microsoft.com, haiyangz@microsoft.com Subject: [PATCH 54/55] drivers: hv: dxgkrnl: Fix crash at hmgrtable_free_handle Date: Thu, 19 Mar 2026 20:25:08 +0000 Message-ID: <20260319202509.63802-55-eric.curtin@docker.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260319202509.63802-1-eric.curtin@docker.com> References: <20260319202509.63802-1-eric.curtin@docker.com> Precedence: bulk X-Mailing-List: linux-hyperv@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Hideyuki Nagase Fix a potential NULL pointer crash in hmgrtable_free_handle() when free_handle_list_tail is HMGRTABLE_INVALID_INDEX. Guard the entry dereference with a bounds check before writing the next_free_index. Signed-off-by: Hideyuki Nagase --- drivers/hv/dxgkrnl/hmgr.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/hv/dxgkrnl/hmgr.c b/drivers/hv/dxgkrnl/hmgr.c index 24101d0091ab..059f94307a0e 100644 --- a/drivers/hv/dxgkrnl/hmgr.c +++ b/drivers/hv/dxgkrnl/hmgr.c @@ -462,9 +462,14 @@ void hmgrtable_free_handle(struct hmgrtable *table, enum hmgrentry_type t, */ entry->next_free_index = HMGRTABLE_INVALID_INDEX; entry->prev_free_index = table->free_handle_list_tail; - entry = &table->entry_table[table->free_handle_list_tail]; - entry->next_free_index = i; + if (table->free_handle_list_tail != HMGRTABLE_INVALID_INDEX) { + entry = &table->entry_table[table->free_handle_list_tail]; + entry->next_free_index = i; + } table->free_handle_list_tail = i; + if (table->free_handle_list_head == HMGRTABLE_INVALID_INDEX) { + table->free_handle_list_head = i; + } } else { DXG_ERR("Invalid handle to free: %d %x", i, h.v); }