Using current HEAD, interrupting a long backtrace results in:

...
#25217 0x0000000000400574 in foo (i=9711) at t.c:1
#25218 0x0000000000400574 in foo (i=9710) at t.c:1
^C../../src/gdb/frame.c:2396: internal-error: frame_cleanup_after_sniffer: Assertion `frame->prologue_cache == NULL' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Aborted (core dumped)


Google ref: b/6486017

Repro steps:

cat t.c
int foo(int i) { char buf[200];  return foo(i + 1) + buf[199]; }
main() { return foo(0); }

gcc -g t.c && gdb ./a.out
GNU gdb (GDB) 7.4.50.20120512-cvs
...

(gdb) run
Starting program: /tmp/a.out 

Program received signal SIGSEGV, Segmentation fault.
0x000000000040054f in foo (i=<error reading variable: Cannot access memory at address 0x7fffff7fefcc>) at t.c:1
1	int foo(int i) { char buf[200];  return foo(i + 1) + buf[199]; }

(gdb) bt    # Hit ^C after a while
...
#25218 0x0000000000400574 in foo (i=9710) at t.c:1
^C../../src/gdb/frame.c:2396: internal-error: frame_cleanup_after_sniffer: Assertion `frame->prologue_cache == NULL' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Aborted (core dumped)


Core was generated by `gdb64-cvs ./a.out'.
Program terminated with signal 6, Aborted.
#0  0x00007f06e115fa75 in *__GI_raise (sig=<optimized out>) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
64	../nptl/sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) bt
#0  0x00007f06e115fa75 in *__GI_raise (sig=<optimized out>) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
#1  0x00007f06e11635c0 in *__GI_abort () at abort.c:92
#2  0x0000000000655126 in dump_core () at ../../src/gdb/utils.c:687
#3  0x0000000000656b7a in internal_vproblem (problem=0xc55350, file=<optimized out>, line=<optimized out>, fmt=<optimized out>, ap=<optimized out>) at ../../src/gdb/utils.c:855
#4  0x0000000000656d49 in internal_verror (file=<optimized out>, line=<optimized out>, fmt=<optimized out>, ap=0x7fff8b32b138) at ../../src/gdb/utils.c:870
#5  0x0000000000656de1 in internal_error (file=0x6896 <Address 0x6896 out of bounds>, line=26774, string=0x6 <Address 0x6 out of bounds>) at ../../src/gdb/utils.c:880
#6  0x00000000006595ce in frame_cleanup_after_sniffer (arg=<optimized out>) at ../../src/gdb/frame.c:2396
#7  0x0000000000542966 in do_my_cleanups (pmy_chain=0xc50888, old_chain=0x8841e0) at ../../src/gdb/cleanups.c:155
#8  0x000000000059bd21 in throw_exception (exception=...) at ../../src/gdb/exceptions.c:227
#9  0x000000000059bced in exceptions_state_mc (action=<optimized out>) at ../../src/gdb/exceptions.c:197
#10 0x000000000065d855 in frame_unwind_find_by_frame (this_frame=<optimized out>, this_cache=<optimized out>) at ../../src/gdb/frame-unwind.c:110
#11 0x00000000006597c1 in get_frame_type (frame=0x92761b0) at ../../src/gdb/frame.c:2226
#12 0x0000000000597498 in print_frame_info (frame=0x92761b0, print_level=1, print_what=LOCATION, print_args=1) at ../../src/gdb/stack.c:767
#13 0x0000000000597b56 in backtrace_command_1 (count_exp=<optimized out>, show_locals=0, from_tty=1) at ../../src/gdb/stack.c:1728
#14 0x0000000000597e83 in backtrace_command (arg=0x0, from_tty=<optimized out>) at ../../src/gdb/stack.c:1804
#15 0x0000000000652a33 in execute_command (p=0x250e9a2 "", from_tty=1) at ../../src/gdb/top.c:484
#16 0x00000000005a4438 in command_handler (command=0x250e9a0 "bt") at ../../src/gdb/event-top.c:435
#17 0x00000000005a4eec in command_line_handler (rl=<optimized out>) at ../../src/gdb/event-top.c:636
#18 0x0000000000694d7b in rl_callback_read_char () at ../../src/readline/callback.c:220
#19 0x00000000005a44a9 in rl_callback_read_char_wrapper (client_data=0x6896) at ../../src/gdb/event-top.c:169
#20 0x00000000005a2dd8 in process_event () at ../../src/gdb/event-loop.c:401
#21 0x00000000005a417a in gdb_do_one_event () at ../../src/gdb/event-loop.c:465
#22 0x00000000005a41e5 in start_event_loop () at ../../src/gdb/event-loop.c:490
#23 0x000000000059d583 in captured_command_loop (data=0x6896) at ../../src/gdb/main.c:226
#24 0x000000000059c0eb in catch_errors (func=<optimized out>, func_args=<optimized out>, errstring=<optimized out>, mask=<optimized out>) at ../../src/gdb/exceptions.c:546
#25 0x000000000059e296 in captured_main (data=<optimized out>) at ../../src/gdb/main.c:1001
#26 0x000000000059c0eb in catch_errors (func=<optimized out>, func_args=<optimized out>, errstring=<optimized out>, mask=<optimized out>) at ../../src/gdb/exceptions.c:546
#27 0x000000000059d544 in gdb_main (args=0x6896) at ../../src/gdb/main.c:1010
#28 0x000000000046fd3e in main (argc=<optimized out>, argv=0x6896) at ../../src/gdb/gdb.c:34