bug#60487: string-ref segfaults with n < 0 on Guile 3.0.8

["Ludovic Courtès" <ludo@gnu.org>]

Hi,

festerdam@posteo.net skribis:

> The following code results in a segmentation fault on Guile
> 3.0.8-deb+3.0.8-2 (obtained from the Debian repositories):
>     (string-ref "my string" -3)

I can reproduce it with 3.0.8, where I get this backtrace:

--8<---------------cut here---------------start------------->8---
scheme@(guile-user)> (string-ref "my string" -3)

Thread 1 "guile" received signal SIGSEGV, Segmentation fault.
0x00007ffff7f419d9 in scm_is_values (x=<optimized out>) at values.h:30
30      values.h: No such file or directory.
(gdb) bt
#0  0x00007ffff7f419d9 in scm_is_values (x=<optimized out>) at values.h:30
#1  vm_debug_engine (thread=0x7ffff75c1d80) at vm-engine.c:974
#2  0x00007ffff7f4c5d9 in scm_call_n (proc=<optimized out>, argv=<optimized out>, nargs=5)
    at vm.c:1610
#3  0x00007ffff7eb8571 in scm_apply_0 (proc=#<program 7ffff5c4e960>, args=()) at eval.c:603
#4  0x00007ffff7f3dc8d in scm_throw (key=out-of-range, 
    args=<error reading variable: ERROR: Cannot access memory at address 0x0>0x7ffff2bb2c30)
    at throw.c:262
#5  0x00007ffff7f3dca9 in scm_ithrow (key=<optimized out>, args=<optimized out>, 
    no_return=<optimized out>) at throw.c:457
#6  0x00007ffff7eb5245 in scm_error_scm (key=key@entry=out-of-range, subr=<optimized out>, 
    message=message@entry="Value out of range ~S to< ~S: ~S", 
    args=args@entry=<error reading variable: ERROR: Cannot access memory at address 0x0>0x7ffff2bb2c70, data=data@entry=(4611686018427387901)) at error.c:90
#7  0x00007ffff7eb52a0 in scm_error (key=out-of-range, subr=0x0, message=<optimized out>, 
    args=<error reading variable: ERROR: Cannot access memory at address 0x0>0x7ffff2bb2c70, 
    rest=(4611686018427387901)) at error.c:62
#8  0x00007ffff7f02dd7 in range_error (bad_val=bad_val@entry=4611686018427387901, 
    min=min@entry=<error reading variable: ERROR: Cannot access memory at address 0x0>0x0, 
    max=#<bignum 7ffff2baeda0>) at numbers.c:6611
#9  0x00007ffff7f04dfb in scm_to_uint64 (arg=4611686018427387901) at integers.c:259
#10 0x00007ffff7f42215 in vm_debug_engine (thread=0x7ffff75c1d80) at vm-engine.c:1533
#11 0x00007ffff7f4c5d9 in scm_call_n (proc=<optimized out>, argv=<optimized out>, nargs=1)
    at vm.c:1610
#12 0x00007ffff7eb4457 in scm_primitive_eval (exp=<optimized out>, 
    exp@entry=((@ (ice-9 control) %) (begin (load-user-init) ((@ (ice-9 top-repl) top-repl)))))
    at eval.c:671
#13 0x00007ffff7eba4b6 in scm_eval (
    exp=((@ (ice-9 control) %) (begin (load-user-init) ((@ (ice-9 top-repl) top-repl)))), 
    module_or_state="#<struct module>" = {...}) at eval.c:705
#14 0x00007ffff7f1e3b6 in scm_shell (argc=1, argv=0x7fffffffd058) at script.c:357
--8<---------------cut here---------------end--------------->8---

Fortunately, this was fixed recently in
c0004442b7691f59a0e37869ef288eb26382ad9e.

Thanks!

Ludo’.