From 3f2baa8a7d2efaa836f1dc4b8ee8c3ca4ba9e101 Mon Sep 17 00:00:00 2001 From: Olaf Hering Date: Thu, 10 Aug 2017 15:45:16 -0700 Subject: [PATCH] Tools: hv: update buffer handling in hv_fcopy_daemon Currently this warning is triggered when compiling hv_fcopy_daemon: hv_fcopy_daemon.c:216:4: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing] kernel_modver = *(__u32 *)buffer; Convert the send/receive buffer to a union and pass individual members as needed. This also gives the correct size for the buffer. Signed-off-by: Olaf Hering Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman --- tools/hv/hv_fcopy_daemon.c | 32 +++++++++++++++++--------------- 1 file changed, 17 insertions(+), 15 deletions(-) diff --git a/tools/hv/hv_fcopy_daemon.c b/tools/hv/hv_fcopy_daemon.c index 26ae609a9448..457a1521f32f 100644 --- a/tools/hv/hv_fcopy_daemon.c +++ b/tools/hv/hv_fcopy_daemon.c @@ -138,14 +138,17 @@ void print_usage(char *argv[]) int main(int argc, char *argv[]) { - int fcopy_fd, len; + int fcopy_fd; int error; int daemonize = 1, long_index = 0, opt; int version = FCOPY_CURRENT_VERSION; - char *buffer[4096 * 2]; - struct hv_fcopy_hdr *in_msg; + union { + struct hv_fcopy_hdr hdr; + struct hv_start_fcopy start; + struct hv_do_fcopy copy; + __u32 kernel_modver; + } buffer = { }; int in_handshake = 1; - __u32 kernel_modver; static struct option long_options[] = { {"help", no_argument, 0, 'h' }, @@ -195,32 +198,31 @@ int main(int argc, char *argv[]) * In this loop we process fcopy messages after the * handshake is complete. */ - len = pread(fcopy_fd, buffer, (4096 * 2), 0); + ssize_t len; + + len = pread(fcopy_fd, &buffer, sizeof(buffer), 0); if (len < 0) { syslog(LOG_ERR, "pread failed: %s", strerror(errno)); exit(EXIT_FAILURE); } if (in_handshake) { - if (len != sizeof(kernel_modver)) { + if (len != sizeof(buffer.kernel_modver)) { syslog(LOG_ERR, "invalid version negotiation"); exit(EXIT_FAILURE); } - kernel_modver = *(__u32 *)buffer; in_handshake = 0; - syslog(LOG_INFO, "kernel module version: %d", - kernel_modver); + syslog(LOG_INFO, "kernel module version: %u", + buffer.kernel_modver); continue; } - in_msg = (struct hv_fcopy_hdr *)buffer; - - switch (in_msg->operation) { + switch (buffer.hdr.operation) { case START_FILE_COPY: - error = hv_start_fcopy((struct hv_start_fcopy *)in_msg); + error = hv_start_fcopy(&buffer.start); break; case WRITE_TO_FILE: - error = hv_copy_data((struct hv_do_fcopy *)in_msg); + error = hv_copy_data(&buffer.copy); break; case COMPLETE_FCOPY: error = hv_copy_finished(); @@ -231,7 +233,7 @@ int main(int argc, char *argv[]) default: syslog(LOG_ERR, "Unknown operation: %d", - in_msg->operation); + buffer.hdr.operation); }