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V4L/DVB (7712): pvrusb2: Close connect/disconnect race 

If a disconnect happens before initialization is completed, the
pvrusb2 driver can accidentally touch dangling pointers.  The whole
initialization function must be protected by the big_lock, and once
inside that lock, the initialization function should abort if it is
discovered that a disconnect has already taken place.

Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
This commit is contained in:
Mike Isely 2008-04-07 02:22:43 -03:00 committed by Mauro Carvalho Chehab
parent e5be15c638
commit 97f26ff604
1 changed files with 10 additions and 1 deletions
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11
drivers/media/video/pvrusb2/pvrusb2-hdw.c
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@ -1854,10 +1854,19 @@ int pvr2_hdw_initialize(struct pvr2_hdw *hdw,
void *callback_data) void *callback_data)
{ {
LOCK_TAKE(hdw->big_lock); do { LOCK_TAKE(hdw->big_lock); do {
if (hdw->flag_disconnected) {
/* Handle a race here: If we're already
disconnected by this point, then give up. If we
get past this then we'll remain connected for
the duration of initialization since the entire
initialization sequence is now protected by the
big_lock. */
break;
}
hdw->state_data = callback_data; hdw->state_data = callback_data;
hdw->state_func = callback_func; hdw->state_func = callback_func;
pvr2_hdw_setup(hdw);
} while (0); LOCK_GIVE(hdw->big_lock); } while (0); LOCK_GIVE(hdw->big_lock);
pvr2_hdw_setup(hdw);
return hdw->flag_init_ok; return hdw->flag_init_ok;
} }