Hi,
Sorry, forgot to reply earlier.
On Tue, Aug 27, 2019 at 03:12:24PM +0300, Uri Lublin wrote:
> 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));
> > > > # ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Here it doesn't say anything about g_memdup() itself (like, if it
took the branch where argv is NULL which means it returns NULL or
if it took the branch wehre argv is not NULL which it does
g_malloc + memcpy, same you suggested.
> > > > 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.
I didn't test it but I trust you that it works. Weird that if
this complain was with the fact that orig_argv is NULL, it should
be more explicit. Doesn't matter much the possible fix as this
still is a false positive, argc is > 0 and argv is not null and
either g_memdup() is going to return valid memory or abort if
ENOMEM.
My 'fix' is just because we really have an extra char* which
seems to be uninitialized.
> 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
> >
>
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