From: Rick Edgecombe rick.p.edgecombe@intel.com

commit 03f5a999adba ("Drivers: hv: vmbus: Leak pages if set_memory_encrypted() fails")

In CoCo VMs it is possible for the untrusted host to cause set_memory_encrypted() or set_memory_decrypted() to fail such that an error is returned and the resulting memory is shared. Callers need to take care to handle these errors to avoid returning decrypted (shared) memory to the page allocator, which could lead to functional or security issues.

VMBus code could free decrypted pages if set_memory_encrypted()/decrypted() fails. Leak the pages if this happens.

Signed-off-by: Rick Edgecombe rick.p.edgecombe@intel.com Signed-off-by: Michael Kelley mhklinux@outlook.com Reviewed-by: Kuppuswamy Sathyanarayanan sathyanarayanan.kuppuswamy@linux.intel.com Acked-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Link: https://lore.kernel.org/r/20240311161558.1310-2-mhklinux@outlook.com Signed-off-by: Wei Liu wei.liu@kernel.org Message-ID: 20240311161558.1310-2-mhklinux@outlook.com Signed-off-by: Sasha Levin sashal@kernel.org

CVE-2024-36913 Signed-off-by: Libo Chen libo.chen.cn@windriver.com --- This commit is backporting 03f5a999adba to the branch linux-5.15.y to solve the CVE-2024-36913. Please merge this commit to linux-5.15.y.

drivers/hv/connection.c | 41 +++++++++++++++++++++++++++++++++++++---- 1 file changed, 37 insertions(+), 4 deletions(-)

diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c index 47fb412eafd3..8283e7ba156e 100644 --- a/drivers/hv/connection.c +++ b/drivers/hv/connection.c @@ -19,6 +19,7 @@ #include <linux/vmalloc.h> #include <linux/hyperv.h> #include <linux/export.h> +#include <linux/set_memory.h> #include <asm/mshyperv.h>

#include "hyperv_vmbus.h" @@ -216,6 +217,29 @@ int vmbus_connect(void) goto cleanup; }

+ ret = set_memory_decrypted((unsigned long) + vmbus_connection.monitor_pages[0], 1); + ret |= set_memory_decrypted((unsigned long) + vmbus_connection.monitor_pages[1], 1); + if (ret) { + /* + * If set_memory_decrypted() fails, the encryption state + * of the memory is unknown. So leak the memory instead + * of risking returning decrypted memory to the free list. + * For simplicity, always handle both pages the same. + */ + vmbus_connection.monitor_pages[0] = NULL; + vmbus_connection.monitor_pages[1] = NULL; + goto cleanup; + } + + /* + * Set_memory_decrypted() will change the memory contents if + * decryption occurs, so zero monitor pages here. + */ + memset(vmbus_connection.monitor_pages[0], 0x00, HV_HYP_PAGE_SIZE); + memset(vmbus_connection.monitor_pages[1], 0x00, HV_HYP_PAGE_SIZE); + msginfo = kzalloc(sizeof(*msginfo) + sizeof(struct vmbus_channel_initiate_contact), GFP_KERNEL); @@ -303,10 +327,19 @@ void vmbus_disconnect(void) vmbus_connection.int_page = NULL; }

- hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[0]); - hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[1]); - vmbus_connection.monitor_pages[0] = NULL; - vmbus_connection.monitor_pages[1] = NULL; + if (vmbus_connection.monitor_pages[0]) { + if (!set_memory_encrypted( + (unsigned long)vmbus_connection.monitor_pages[0], 1)) + hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[0]); + vmbus_connection.monitor_pages[0] = NULL; + } + + if (vmbus_connection.monitor_pages[1]) { + if (!set_memory_encrypted( + (unsigned long)vmbus_connection.monitor_pages[1], 1)) + hv_free_hyperv_page((unsigned long)vmbus_connection.monitor_pages[1]); + vmbus_connection.monitor_pages[1] = NULL; + } }

/*