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Bug fix: Fix access to freed memory due to invalid w->prev_trans

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- Fix a bug that w->prev_trans sometimes points to freed memory.
  Probably related to #165.

- Add some more debugging printf()-s under DEBUG_EVENTS.
This commit is contained in:
Richard Grenville 2014-01-21 22:13:06 +08:00
parent f1f7b050af
commit aeda1482ce
1 changed files with 28 additions and 1 deletions
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29
src/compton.c
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@ -1245,6 +1245,7 @@ paint_preprocess(session_t *ps, win *list) {
t = w; t = w;
} }
else { else {
assert(w->destroyed == (w->fade_callback == destroy_callback));
check_fade_fin(ps, w); check_fade_fin(ps, w);
} }
@ -2089,6 +2090,10 @@ map_win(session_t *ps, Window id) {
win *w = find_win(ps, id); win *w = find_win(ps, id);
#ifdef DEBUG_EVENTS
printf_dbgf("(%#010lx \"%s\"): %p\n", id, (w ? w->name: NULL), w);
#endif
// Don't care about window mapping if it's an InputOnly window // Don't care about window mapping if it's an InputOnly window
// Try avoiding mapping a window twice // Try avoiding mapping a window twice
if (!w || InputOnly == w->a.class if (!w || InputOnly == w->a.class
@ -2824,6 +2829,10 @@ add_win(session_t *ps, Window id, Window prev) {
// Allocate and initialize the new win structure // Allocate and initialize the new win structure
win *new = malloc(sizeof(win)); win *new = malloc(sizeof(win));
#ifdef DEBUG_EVENTS
printf_dbgf("(%#010lx): %p\n", id, new);
#endif
if (!new) { if (!new) {
printf_errf("(%#010lx): Failed to allocate memory for the new window.", id); printf_errf("(%#010lx): Failed to allocate memory for the new window.", id);
return false; return false;
@ -3078,10 +3087,18 @@ circulate_win(session_t *ps, XCirculateEvent *ce) {
static void static void
finish_destroy_win(session_t *ps, Window id) { finish_destroy_win(session_t *ps, Window id) {
win **prev, *w; win **prev = NULL, *w = NULL;
#ifdef DEBUG_EVENTS
printf_dbgf("(%#010lx): Starting...\n", id);
#endif
for (prev = &ps->list; (w = *prev); prev = &w->next) { for (prev = &ps->list; (w = *prev); prev = &w->next) {
if (w->id == id && w->destroyed) { if (w->id == id && w->destroyed) {
#ifdef DEBUG_EVENTS
printf_dbgf("(%#010lx \"%s\"): %p\n", id, w->name, w);
#endif
finish_unmap_win(ps, w); finish_unmap_win(ps, w);
*prev = w->next; *prev = w->next;
@ -3091,6 +3108,12 @@ finish_destroy_win(session_t *ps, Window id) {
free_win_res(ps, w); free_win_res(ps, w);
// Drop w from all prev_trans to avoid accessing freed memory in
// repair_win()
for (win *w2 = ps->list; w2; w2 = w2->next)
if (w == w2->prev_trans)
w2->prev_trans = NULL;
free(w); free(w);
break; break;
} }
@ -3106,6 +3129,10 @@ static void
destroy_win(session_t *ps, Window id) { destroy_win(session_t *ps, Window id) {
win *w = find_win(ps, id); win *w = find_win(ps, id);
#ifdef DEBUG_EVENTS
printf_dbgf("(%#010lx \"%s\"): %p\n", id, (w ? w->name: NULL), w);
#endif
if (w) { if (w) {
unmap_win(ps, w); unmap_win(ps, w);