src/openvt.c:386: 'pid' may be used uninitialized

Hi,

I've found this bug using a static analyzer (slightly improved GCC).

Consider variable pid in function main from src/openvt.c:

src/openvt.c:166:       int opt, pid, i;
src/openvt.c:303:       if (direct_exec || ((pid = fork()) == 0)) {
src/openvt.c:386:       if (pid < 0)

src/openvt.c:393: waitpid(pid, &retval, 0);

If direct_exec is TRUE, then pid doesn't get initialized, but it is used outside the conditional regardless of that.

Quoted 11 lines

Hi,

I've found this bug using a static analyzer (slightly improved GCC).

Consider variable pid in function main from src/openvt.c:

src/openvt.c:166:       int opt, pid, i;
src/openvt.c:303:       if (direct_exec || ((pid = fork()) == 0)) {
src/openvt.c:386:       if (pid < 0)

src/openvt.c:393: waitpid(pid, &retval, 0);

Quoted 2 lines

If direct_exec is TRUE, then pid doesn't get initialized, but it is used outside the conditional regardless of that.

This is not a bug. If direct_exec is TRUE we will never be on line 386.

To make linter happy, I’ll make pid = 0.

Thanks!

Signature · 1 line

Rgrds, legion

Sorry, I didn't get your reply (not sure what the actual reason is, but it seems as if you've only replied to the list, and I am not subscribed) so I've just read it today in the archives.

Quoted 12 lines · Vladislav Ivanishin

Quoted 11 lines

Hi,

I've found this bug using a static analyzer (slightly improved GCC).

Consider variable pid in function main from src/openvt.c:

src/openvt.c:166:       int opt, pid, i;
src/openvt.c:303:       if (direct_exec || ((pid = fork()) == 0)) {
src/openvt.c:386:       if (pid < 0)

src/openvt.c:393: waitpid(pid, &retval, 0);

Quoted 4 lines

Quoted 2 lines

If direct_exec is TRUE, then pid doesn't get initialized, but it is used outside the conditional regardless of that.

This is not a bug. If direct_exec is TRUE we will never be on line 386.

Oh, I didn't realize that; my bad, thanks for pointing this out.

The real issue preventing the analyzer (i.e. the compiler) from seeing this as well is kbd_error lacking the noreturn attribute.

Quoted 1 line

To make linter happy, I’ll make pid = 0.

So a more proper fix would be adding the attribute in the header file. It would also make other compiler analyses/optimizations more effective.