| Message ID | 20230720134429.1419479-1-josimmon@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v6] vfprintf-internal: Get rid of alloca. | expand |
On 20/07/23 10:44, Joe Simmons-Talbott via Libc-alpha wrote: > Avoid potential stack overflow from unbounded alloca. Use the existing > scratch_buffer instead. > > Add testcases to exercise the code as suggested by Adhemerval Zanella Netto. LGTM, thanks. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> > --- > Changes to v5: > * Remove unneeded printf and add more tests for various argument > counts. > > stdio-common/tst-vfprintf-user-type.c | 130 ++++++++++++++++++++++++++ > stdio-common/vfprintf-internal.c | 23 ++++- > 2 files changed, 152 insertions(+), 1 deletion(-) > > diff --git a/stdio-common/tst-vfprintf-user-type.c b/stdio-common/tst-vfprintf-user-type.c > index 7cc69dc716..adcbf33c20 100644 > --- a/stdio-common/tst-vfprintf-user-type.c > +++ b/stdio-common/tst-vfprintf-user-type.c > @@ -194,6 +194,136 @@ do_test (void) > TEST_COMPARE_STRING (str, "[[(123, 457.000000) (123, 457.000000)]]"); > free (str); > > + str = NULL; > + TEST_VERIFY (asprintf_alias (&str, "%1$P %2$P %3$P %4$P %5$P %6$P", > + 1L, 1.0, > + 2L, 2.0, > + 3L, 3.0, > + 4L, 4.0, > + 5L, 6.0, > + 6L, 6.0) > + >= 0); > + free (str); > + > + str = NULL; > + TEST_VERIFY (asprintf_alias (&str, "%1$P %2$P %3$P %4$P %5$P %6$P" > + "%7$P %8$P %9$P %10$P %11$P %12$P", > + 1L, 1.0, > + 2L, 2.0, > + 3L, 3.0, > + 4L, 4.0, > + 5L, 6.0, > + 6L, 6.0, > + 7L, 7.0, > + 8L, 8.0, > + 9L, 9.0, > + 10L, 10.0, > + 11L, 11.0, > + 12L, 12.0) > + >= 0); > + free (str); > + > + str = NULL; > + TEST_VERIFY (asprintf_alias (&str, "%1$P %2$P %3$P %4$P %5$P %6$P" > + "%7$P %8$P %9$P %10$P %11$P %12$P" > + "%13$P %14$P %15$P %16$P %17$P %18$P", > + 1L, 1.0, > + 2L, 2.0, > + 3L, 3.0, > + 4L, 4.0, > + 5L, 6.0, > + 6L, 6.0, > + 7L, 7.0, > + 8L, 8.0, > + 9L, 9.0, > + 10L, 10.0, > + 11L, 11.0, > + 12L, 12.0, > + 13L, 13.0, > + 14L, 14.0, > + 15L, 15.0, > + 16L, 16.0, > + 17L, 17.0, > + 18L, 18.0) > + >= 0); > + free (str); > + > + str = NULL; > + TEST_VERIFY (asprintf_alias (&str, "%1$P %2$P %3$P %4$P %5$P %6$P" > + "%7$P %8$P %9$P %10$P %11$P %12$P" > + "%13$P %14$P %15$P %16$P %17$P %18$P" > + "%19$P %20$P %21$P %22$P %23$P %24$P", > + 1L, 1.0, > + 2L, 2.0, > + 3L, 3.0, > + 4L, 4.0, > + 5L, 6.0, > + 6L, 6.0, > + 7L, 7.0, > + 8L, 8.0, > + 9L, 9.0, > + 10L, 10.0, > + 11L, 11.0, > + 12L, 12.0, > + 13L, 13.0, > + 14L, 14.0, > + 15L, 15.0, > + 16L, 16.0, > + 17L, 17.0, > + 18L, 18.0, > + 19L, 19.0, > + 20L, 20.0, > + 21L, 21.0, > + 22L, 22.0, > + 23L, 23.0, > + 24L, 24.0) > + >= 0); > + free (str); > + > + str = NULL; > + TEST_VERIFY (asprintf_alias (&str, "%1$P %2$P %3$P %4$P %5$P %6$P" > + "%7$P %8$P %9$P %10$P %11$P %12$P" > + "%13$P %14$P %15$P %16$P %17$P %18$P" > + "%19$P %20$P %21$P %22$P %23$P %24$P" > + "%25$P %26$P %27$P %28$P %29$P %30$P", > + 1L, 1.0, > + 2L, 2.0, > + 3L, 3.0, > + 4L, 4.0, > + 5L, 6.0, > + 6L, 6.0, > + 7L, 7.0, > + 8L, 8.0, > + 9L, 9.0, > + 10L, 10.0, > + 11L, 11.0, > + 12L, 12.0, > + 13L, 13.0, > + 14L, 14.0, > + 15L, 15.0, > + 16L, 16.0, > + 17L, 17.0, > + 18L, 18.0, > + 19L, 19.0, > + 20L, 20.0, > + 21L, 21.0, > + 22L, 22.0, > + 23L, 23.0, > + 24L, 34.0, > + 25L, 25.0, > + 26L, 26.0, > + 27L, 27.0, > + 28L, 28.0, > + 29L, 29.0, > + 30, 30.0) > + >= 0); > + free (str); > + > + str = NULL; > + TEST_VERIFY (asprintf_alias (&str, "[[%1$P %1$P]]", 123L, 457.0) >= 0); > + TEST_COMPARE_STRING (str, "[[(123, 457.000000) (123, 457.000000)]]"); > + free (str); > + > str = NULL; > TEST_VERIFY (asprintf_alias (&str, "[[%.1P]]", 1L, 2.0) >= 0); > TEST_COMPARE_STRING (str, "[[{(1, 2.000000)}]]"); > diff --git a/stdio-common/vfprintf-internal.c b/stdio-common/vfprintf-internal.c > index f30a9e9f3a..6d6d96e800 100644 > --- a/stdio-common/vfprintf-internal.c > +++ b/stdio-common/vfprintf-internal.c > @@ -1130,6 +1130,8 @@ printf_positional (struct Xprintf_buffer * buf, const CHAR_T *format, > union printf_arg *args_value; > int *args_size; > int *args_type; > + void *args_pa_user; > + size_t args_pa_user_offset; > { > /* Calculate total size needed to represent a single argument > across all three argument-related arrays. */ > @@ -1146,6 +1148,7 @@ printf_positional (struct Xprintf_buffer * buf, const CHAR_T *format, > now. */ > args_size = &args_value[nargs].pa_int; > args_type = &args_size[nargs]; > + args_pa_user = &args_type[nargs]; > memset (args_type, (mode_flags & PRINTF_FORTIFY) != 0 ? '\xff' : '\0', > nargs * sizeof (*args_type)); > } > @@ -1235,7 +1238,25 @@ printf_positional (struct Xprintf_buffer * buf, const CHAR_T *format, > else if (__glibc_unlikely (__printf_va_arg_table != NULL) > && __printf_va_arg_table[args_type[cnt] - PA_LAST] != NULL) > { > - args_value[cnt].pa_user = alloca (args_size[cnt]); > + while (args_pa_user + args_size[cnt] > > + argsbuf.data + argsbuf.length) > + { > + args_pa_user_offset = args_pa_user - (void *) &args_type[nargs]; > + if (!scratch_buffer_grow_preserve (&argsbuf)) > + { > + Xprintf_buffer_mark_failed (buf); > + goto all_done; > + } > + args_value = argsbuf.data; > + /* Set up the remaining two arrays to each point past the end of > + the prior array, since space for all three has been allocated > + now. */ > + args_size = &args_value[nargs].pa_int; > + args_type = &args_size[nargs]; > + args_pa_user = (void *) &args_type[nargs] + args_pa_user_offset; > + } > + args_value[cnt].pa_user = args_pa_user; > + args_pa_user += args_size[cnt]; > (*__printf_va_arg_table[args_type[cnt] - PA_LAST]) > (args_value[cnt].pa_user, ap_savep); > }
diff --git a/stdio-common/tst-vfprintf-user-type.c b/stdio-common/tst-vfprintf-user-type.c index 7cc69dc716..adcbf33c20 100644 --- a/stdio-common/tst-vfprintf-user-type.c +++ b/stdio-common/tst-vfprintf-user-type.c @@ -194,6 +194,136 @@ do_test (void) TEST_COMPARE_STRING (str, "[[(123, 457.000000) (123, 457.000000)]]"); free (str); + str = NULL; + TEST_VERIFY (asprintf_alias (&str, "%1$P %2$P %3$P %4$P %5$P %6$P", + 1L, 1.0, + 2L, 2.0, + 3L, 3.0, + 4L, 4.0, + 5L, 6.0, + 6L, 6.0) + >= 0); + free (str); + + str = NULL; + TEST_VERIFY (asprintf_alias (&str, "%1$P %2$P %3$P %4$P %5$P %6$P" + "%7$P %8$P %9$P %10$P %11$P %12$P", + 1L, 1.0, + 2L, 2.0, + 3L, 3.0, + 4L, 4.0, + 5L, 6.0, + 6L, 6.0, + 7L, 7.0, + 8L, 8.0, + 9L, 9.0, + 10L, 10.0, + 11L, 11.0, + 12L, 12.0) + >= 0); + free (str); + + str = NULL; + TEST_VERIFY (asprintf_alias (&str, "%1$P %2$P %3$P %4$P %5$P %6$P" + "%7$P %8$P %9$P %10$P %11$P %12$P" + "%13$P %14$P %15$P %16$P %17$P %18$P", + 1L, 1.0, + 2L, 2.0, + 3L, 3.0, + 4L, 4.0, + 5L, 6.0, + 6L, 6.0, + 7L, 7.0, + 8L, 8.0, + 9L, 9.0, + 10L, 10.0, + 11L, 11.0, + 12L, 12.0, + 13L, 13.0, + 14L, 14.0, + 15L, 15.0, + 16L, 16.0, + 17L, 17.0, + 18L, 18.0) + >= 0); + free (str); + + str = NULL; + TEST_VERIFY (asprintf_alias (&str, "%1$P %2$P %3$P %4$P %5$P %6$P" + "%7$P %8$P %9$P %10$P %11$P %12$P" + "%13$P %14$P %15$P %16$P %17$P %18$P" + "%19$P %20$P %21$P %22$P %23$P %24$P", + 1L, 1.0, + 2L, 2.0, + 3L, 3.0, + 4L, 4.0, + 5L, 6.0, + 6L, 6.0, + 7L, 7.0, + 8L, 8.0, + 9L, 9.0, + 10L, 10.0, + 11L, 11.0, + 12L, 12.0, + 13L, 13.0, + 14L, 14.0, + 15L, 15.0, + 16L, 16.0, + 17L, 17.0, + 18L, 18.0, + 19L, 19.0, + 20L, 20.0, + 21L, 21.0, + 22L, 22.0, + 23L, 23.0, + 24L, 24.0) + >= 0); + free (str); + + str = NULL; + TEST_VERIFY (asprintf_alias (&str, "%1$P %2$P %3$P %4$P %5$P %6$P" + "%7$P %8$P %9$P %10$P %11$P %12$P" + "%13$P %14$P %15$P %16$P %17$P %18$P" + "%19$P %20$P %21$P %22$P %23$P %24$P" + "%25$P %26$P %27$P %28$P %29$P %30$P", + 1L, 1.0, + 2L, 2.0, + 3L, 3.0, + 4L, 4.0, + 5L, 6.0, + 6L, 6.0, + 7L, 7.0, + 8L, 8.0, + 9L, 9.0, + 10L, 10.0, + 11L, 11.0, + 12L, 12.0, + 13L, 13.0, + 14L, 14.0, + 15L, 15.0, + 16L, 16.0, + 17L, 17.0, + 18L, 18.0, + 19L, 19.0, + 20L, 20.0, + 21L, 21.0, + 22L, 22.0, + 23L, 23.0, + 24L, 34.0, + 25L, 25.0, + 26L, 26.0, + 27L, 27.0, + 28L, 28.0, + 29L, 29.0, + 30, 30.0) + >= 0); + free (str); + + str = NULL; + TEST_VERIFY (asprintf_alias (&str, "[[%1$P %1$P]]", 123L, 457.0) >= 0); + TEST_COMPARE_STRING (str, "[[(123, 457.000000) (123, 457.000000)]]"); + free (str); + str = NULL; TEST_VERIFY (asprintf_alias (&str, "[[%.1P]]", 1L, 2.0) >= 0); TEST_COMPARE_STRING (str, "[[{(1, 2.000000)}]]"); diff --git a/stdio-common/vfprintf-internal.c b/stdio-common/vfprintf-internal.c index f30a9e9f3a..6d6d96e800 100644 --- a/stdio-common/vfprintf-internal.c +++ b/stdio-common/vfprintf-internal.c @@ -1130,6 +1130,8 @@ printf_positional (struct Xprintf_buffer * buf, const CHAR_T *format, union printf_arg *args_value; int *args_size; int *args_type; + void *args_pa_user; + size_t args_pa_user_offset; { /* Calculate total size needed to represent a single argument across all three argument-related arrays. */ @@ -1146,6 +1148,7 @@ printf_positional (struct Xprintf_buffer * buf, const CHAR_T *format, now. */ args_size = &args_value[nargs].pa_int; args_type = &args_size[nargs]; + args_pa_user = &args_type[nargs]; memset (args_type, (mode_flags & PRINTF_FORTIFY) != 0 ? '\xff' : '\0', nargs * sizeof (*args_type)); } @@ -1235,7 +1238,25 @@ printf_positional (struct Xprintf_buffer * buf, const CHAR_T *format, else if (__glibc_unlikely (__printf_va_arg_table != NULL) && __printf_va_arg_table[args_type[cnt] - PA_LAST] != NULL) { - args_value[cnt].pa_user = alloca (args_size[cnt]); + while (args_pa_user + args_size[cnt] > + argsbuf.data + argsbuf.length) + { + args_pa_user_offset = args_pa_user - (void *) &args_type[nargs]; + if (!scratch_buffer_grow_preserve (&argsbuf)) + { + Xprintf_buffer_mark_failed (buf); + goto all_done; + } + args_value = argsbuf.data; + /* Set up the remaining two arrays to each point past the end of + the prior array, since space for all three has been allocated + now. */ + args_size = &args_value[nargs].pa_int; + args_type = &args_size[nargs]; + args_pa_user = (void *) &args_type[nargs] + args_pa_user_offset; + } + args_value[cnt].pa_user = args_pa_user; + args_pa_user += args_size[cnt]; (*__printf_va_arg_table[args_type[cnt] - PA_LAST]) (args_value[cnt].pa_user, ap_savep); }