From 583150198b78c84d043455b0afcca58a9659eab3 Mon Sep 17 00:00:00 2001 From: Peter Wu Date: Sun, 11 Sep 2016 01:16:24 +0200 Subject: extcap: fix use-after-free for preferences In commit v2.3.0rc0-117-g485bc45 (backported to v2.2.0rc0-44-g66721ca), extcap_prefs_dynamic_vals and extcap_cleanup were added in an attempt to address dangling pointers. Unfortunately it is not sufficient: - A pointer to the preference value is stored in extcap_arg and passed to the prefs API, but this extcap_arg structure can become invalid which result in use-after-free whenever the preference is accessed. - On exit, a use-after-free occurs in prefs_cleanup when the preference value is being checked. As the preference subsystem actually manages the memory for the string value and consumers should only provide a pointer where the value can be stored, convert the char* field in extcap to char**. This has as additional benefit that values are not limited to 256 bytes anymore. extcap_cleanup is moved after epan_cleanup to ensure that prefs_cleanup does not operate on dangling pointers. Crash is reproducible under ASAN with: tshark -i randpkt Ping-Bug: 12183 Change-Id: Ibf1ba1102a5633aa085dc278a12ffc05a4f4a34b Reviewed-on: https://code.wireshark.org/review/17631 Petri-Dish: Peter Wu Tested-by: Petri Dish Buildbot Reviewed-by: Roland Knall --- extcap.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'extcap.h') diff --git a/extcap.h b/extcap.h index 5a78d214d8..dd39247dd0 100644 --- a/extcap.h +++ b/extcap.h @@ -113,7 +113,11 @@ void extcap_pref_store(struct _extcap_arg * arg, const char * newval); /* Clean up global extcap stuff on program exit */ +#ifdef HAVE_EXTCAP void extcap_cleanup(void); +#else +static inline void extcap_cleanup(void) {} +#endif #ifdef __cplusplus } -- cgit v1.2.1