Re: [linux/vd_agent v1 1/2] covscan: check and initialize argv's copy

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 8/27/19 1:27 PM, Frediano Ziglio wrote:

From: Victor Toso <me@xxxxxxxxxxxxxx>

Otherwise we get a CLANG_WARNING due accessing garbage.

Covscan report:
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:471:9: warning: 1st function
  > call argument is an uninitialized value
  > #        execvp(orig_argv[0], orig_argv);
  > #        ^      ~~~~~~~~~~~~
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:421:24: note: Storing
  > uninitialized value
  > #    char **orig_argv = g_memdup(argv, sizeof(char*) * (argc+1));
  > #                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:434:9: note: Assuming 'error'
  > is equal to NULL
  > #    if (error != NULL) {
  > #        ^~~~~~~~~~~~~
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:434:5: note: Taking false
  > branch
  > #    if (error != NULL) {
  > #    ^
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:442:9: note: Assuming 'portdev'
  > is not equal to NULL
  > #    if (portdev == NULL)
  > #        ^~~~~~~~~~~~~~~
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:442:5: note: Taking false
  > branch
  > #    if (portdev == NULL)
  > #    ^
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:445:9: note: Assuming
  > 'vdagentd_socket' is not equal to NULL
  > #    if (vdagentd_socket == NULL)
  > #        ^~~~~~~~~~~~~~~~~~~~~~~
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:445:5: note: Taking false
  > branch
  > #    if (vdagentd_socket == NULL)
  > #    ^
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:448:30: note: Assuming
  > 'do_daemonize' is 0
  > #    openlog("spice-vdagent", do_daemonize ? LOG_PID : (LOG_PID |
  > LOG_PERROR),
  > #                             ^~~~~~~~~~~~
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:448:30: note: '?' condition is
  > false
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:451:9: note: Assuming the
  > condition is false
  > #    if (!g_file_test(portdev, G_FILE_TEST_EXISTS)) {
  > #        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:451:5: note: Taking false
  > branch
  > #    if (!g_file_test(portdev, G_FILE_TEST_EXISTS)) {
  > #    ^
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:457:9: note: Assuming
  > 'do_daemonize' is 0
  > #    if (do_daemonize)
  > #        ^~~~~~~~~~~~
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:457:5: note: Taking false
  > branch
  > #    if (do_daemonize)
  > #    ^
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:468:9: note: Assuming
  > 'version_mismatch' is not equal to 0
  > #    if (version_mismatch) {
  > #        ^~~~~~~~~~~~~~~~
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:468:5: note: Taking true branch
  > #    if (version_mismatch) {
  > #    ^
  > spice-vdagent-0.19.0/src/vdagent/vdagent.c:471:9: note: 1st function call
  > argument is an uninitialized value
  > #        execvp(orig_argv[0], orig_argv);
  > #        ^      ~~~~~~~~~~~~
  > #  469|           syslog(LOG_INFO, "Version mismatch, restarting");
  > #  470|           sleep(1);
  > #  471|->         execvp(orig_argv[0], orig_argv);
  > #  472|       }
  > #  473|

Signed-off-by: Victor Toso <victortoso@xxxxxxxxxx>
---
  src/vdagent/vdagent.c | 6 +++++-
  1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/vdagent/vdagent.c b/src/vdagent/vdagent.c
index 0e2e73e..982fc72 100644
--- a/src/vdagent/vdagent.c
+++ b/src/vdagent/vdagent.c
@@ -418,7 +418,11 @@ int main(int argc, char *argv[])
      GOptionContext *context;
      GError *error = NULL;
      VDAgent *agent;
-    char **orig_argv = g_memdup(argv, sizeof(char*) * (argc+1));
+    char **orig_argv;
+
+    g_return_val_if_fail(argc > 0 && argv != NULL, -1);
+    orig_argv = g_memdup(argv, sizeof(char*) * (argc+1));

Hi,

I was able to "fix" it by replacing g_memdup with g_malloc + memcpy
-    char **orig_argv = g_memdup(argv, sizeof(char*) * (argc+1));
+    char **orig_argv = g_malloc(sizeof(char*) * (argc+1) );
+    memcpy(orig_argv, argv, sizeof(char*) * (argc+1) );

So clang seems to be confused by "side effects" of g_memdup.

Uri.

+    orig_argv[argc] = NULL;
context = g_option_context_new(NULL);
      g_option_context_add_main_entries(context, entries, NULL);

I would say better to disable Clang test instead. The code is perfectly
fine. argc is at least 1 (the executable name!) and argv is always terminated
with NULL (that's the standard!).
See https://clang-analyzer.llvm.org/faq.html.

I don't know where this -1 come, but EXIT_FAILURE (which is usually 1) is the standard
return for main function.

Frediano
_______________________________________________
Spice-devel mailing list
Spice-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/spice-devel


_______________________________________________
Spice-devel mailing list
Spice-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/spice-devel




[Index of Archives]     [Linux Virtualization]     [Linux Virtualization]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux OMAP]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]     [Monitors]