events: do not read garbage memory on empty control files #724

pkova · 2024-10-03T13:42:57Z

This is another one of the address sanitizer catches.

For whatever reason my directed messaging fakeship ended up in a situation with empty control.bin and memory.bin. When starting up this fakeship the address sanitizer blows up here:

vere/pkg/noun/events.c

Lines 459 to 467 in f5799a9

    
           pat_u->con_u = c3_malloc(len_w); 
        
           if ( (len_w != read(pat_u->ctl_i, pat_u->con_u, len_w)) || 
        
                 (len_w != sizeof(u3e_control) + 
        
                           (pat_u->con_u->pgs_w * sizeof(u3e_line))) ) 
        
           { 
        
             c3_free(pat_u->con_u); 
        
             pat_u->con_u = 0; 
        
             return c3n; 
        
           }

len_w is 0, malloc(0) is implementation defined but does give a non-null pointer on macos, which means that on line 462 we are reading random garbage.

events: do not read garbage memory on empty control files

174f35b

pkova requested a review from a team as a code owner October 3, 2024 13:42

pkova merged commit ec54a66 into develop Oct 4, 2024
5 checks passed

pkova deleted the pkova/control branch October 4, 2024 15:24

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

events: do not read garbage memory on empty control files #724

events: do not read garbage memory on empty control files #724

pkova commented Oct 3, 2024

	pat_u->con_u = c3_malloc(len_w);
	if ( (len_w != read(pat_u->ctl_i, pat_u->con_u, len_w)) \|\|
	(len_w != sizeof(u3e_control) +
	(pat_u->con_u->pgs_w * sizeof(u3e_line))) )
	{
	c3_free(pat_u->con_u);
	pat_u->con_u = 0;
	return c3n;
	}

events: do not read garbage memory on empty control files #724

events: do not read garbage memory on empty control files #724

Conversation

pkova commented Oct 3, 2024