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From: Corinna Vinschen <corinna@sourceware.org> To: cygwin-cvs@sourceware.org Subject: [newlib-cygwin] Cygwin: posix timers: allocate timer_tracker on system heap. Date: Tue, 22 Jan 2019 15:38:00 -0000 [thread overview] Message-ID: <20190122153840.66238.qmail@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=83c51fffe6bad36a7143c30946ac5445f9ca4c56 commit 83c51fffe6bad36a7143c30946ac5445f9ca4c56 Author: Corinna Vinschen <corinna@vinschen.de> Date: Tue Jan 22 16:22:45 2019 +0100 Cygwin: posix timers: allocate timer_tracker on system heap. Allocating on the cygheap would copy information of the tracker into the child process. A forked child knows the timer id and could simply still access the (free'd but still valid) timer_tracker on the heap, which is dangerous and very certainly doesn't reflect POSIX semantics. Signed-off-by: Corinna Vinschen <corinna@vinschen.de> Diff: --- winsup/cygwin/cygheap_malloc.h | 3 +-- winsup/cygwin/posix_timer.cc | 5 +++-- winsup/cygwin/posix_timer.h | 2 +- 3 files changed, 5 insertions(+), 5 deletions(-) diff --git a/winsup/cygwin/cygheap_malloc.h b/winsup/cygwin/cygheap_malloc.h index cd545c3..74f0bb6 100644 --- a/winsup/cygwin/cygheap_malloc.h +++ b/winsup/cygwin/cygheap_malloc.h @@ -34,8 +34,7 @@ enum cygheap_types HEAP_2_DLL, HEAP_MMAP, HEAP_2_MAX = 200, - HEAP_3_FHANDLER, - HEAP_3_TIMER + HEAP_3_FHANDLER }; extern "C" { diff --git a/winsup/cygwin/posix_timer.cc b/winsup/cygwin/posix_timer.cc index 8651c22..e969dcc 100644 --- a/winsup/cygwin/posix_timer.cc +++ b/winsup/cygwin/posix_timer.cc @@ -414,10 +414,11 @@ timer_tracker::settime (int flags, const itimerspec *new_value, return ret; } -/* The timers are stored on the cygheap. */ +/* The timers are stored on the system heap in order to avoid accidental + leaking of timer ids into the child process. */ #define cnew(name, ...) \ ({ \ - void* ptr = (void*) ccalloc (HEAP_3_TIMER, 1, sizeof (name)); \ + void* ptr = (void*) HeapAlloc (GetProcessHeap (), 0, sizeof (name)); \ ptr ? new (ptr) name (__VA_ARGS__) : NULL; \ }) diff --git a/winsup/cygwin/posix_timer.h b/winsup/cygwin/posix_timer.h index 04a383f..f69a179 100644 --- a/winsup/cygwin/posix_timer.h +++ b/winsup/cygwin/posix_timer.h @@ -30,7 +30,7 @@ class timer_tracker public: void *operator new (size_t, void *p) __attribute__ ((nothrow)) {return p;} - void operator delete (void *p) { cfree (p); } + void operator delete (void *p) { HeapFree (GetProcessHeap (), 0, p); } timer_tracker (clockid_t, const sigevent *); ~timer_tracker (); inline bool is_timer_tracker () const { return magic == TT_MAGIC; }
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