bug#78880: od Heap-buffer overflow
Paul Eggert <[email protected]>
| Newsgroups | gmane.comp.gnu.core-utils.bugs |
|---|---|
| Organization | UCLA Computer Science Department |
| Message-ID | <[email protected]> |
On 2025-06-29 05:17, Pádraig Brady wrote: > If we want the compiler to just apply Dead Code Elimination here, > then it may be best to push/pop ignoring that warning ? Or, since GCC didn't complain about similar code elsewhere, we can change the complained-about code to look more like the code elsewhere. This is more likely to pacify any non-GCC compilers that are also flummoxed. There's a similar situation with the floating point formats, which I assume you didn't run into because they're all distinct on your platform. I installed the attached patch which I hope pacifies GCC on your platform. I didn't observe the problem with gcc (GCC) 15.1.1 20250521 (Red Hat 15.1.1-2) on x86-64 so I can't easily test the patch myself.
0001-od-pacify-gcc-Wduplicated-cond.patch
(text/x-patch, 5.9 KB)
From dcdb2550c4a6480394fa3b6303a81c7f94461865 Mon Sep 17 00:00:00 2001 From: Paul Eggert <[email protected]> Date: Sun, 29 Jun 2025 17:12:07 -0700 Subject: [PATCH] od: pacify gcc -Wduplicated-cond MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Problem reported by Pádraig Brady <https://bugs.gnu.org/78880#43>. This patch doesn’t fix any bugs; it merely pacifies GCC. * src/od.c (ispec_to_format): New function, replacing the old ISPEC_TO_FORMAT macro. All uses changed. This part of the change is just refactoring. (decode_one_format): Pacify à la ispec_to_format. --- src/od.c | 56 +++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 35 insertions(+), 21 deletions(-) diff --git a/src/od.c b/src/od.c index 50319aa83..3381ee484 100644 --- a/src/od.c +++ b/src/od.c @@ -668,6 +668,21 @@ simple_strtoi (char const *s, char const **p, int *val) return true; } +/* Return a printf format for SPEC, given that remaining arguments are + formats for int, long, long long, and intmax_t, respectively. */ +static char const * +ispec_to_format (enum size_spec size_spec, + char const *int_format, + char const *long_format, + char const *long_long_format, + char const *intmax_format) +{ + return (LONG < INTMAX && size_spec == INTMAX ? intmax_format + : LONG < LONG_LONG && size_spec == LONG_LONG ? long_long_format + : INT < LONG && size_spec == LONG ? long_format + : int_format); +} + /* If S points to a single valid modern od format string, put a description of that format in *TSPEC, make *NEXT point at the character following the just-decoded format (if *NEXT is non-null), @@ -756,12 +771,6 @@ decode_one_format (char const *s_orig, char const *s, char const **next, break; } -#define ISPEC_TO_FORMAT(Spec, Min_fmt, Long_fmt, Long_long_fmt, Max_fmt) \ - (LONG < INTMAX && (Spec) == INTMAX ? (Max_fmt) \ - : LONG < LONG_LONG && (Spec) == LONG_LONG ? (Long_long_fmt) \ - : INT < LONG && (Spec) == LONG ? (Long_fmt) \ - : (Min_fmt)) - size_spec = integral_type_size[size]; switch (c) @@ -770,28 +779,28 @@ decode_one_format (char const *s_orig, char const *s, char const **next, fmt = SIGNED_DECIMAL; field_width = INT_BITS_STRLEN_BOUND (CHAR_BIT * size - 1) + 1; sprintf (tspec->fmt_string, "%%*%s", - ISPEC_TO_FORMAT (size_spec, "d", "ld", "lld", "jd")); + ispec_to_format (size_spec, "d", "ld", "lld", "jd")); break; case 'o': fmt = OCTAL; field_width = (CHAR_BIT * size + 2) / 3; sprintf (tspec->fmt_string, "%%*.%d%s", field_width, - ISPEC_TO_FORMAT (size_spec, "o", "lo", "llo", "jo")); + ispec_to_format (size_spec, "o", "lo", "llo", "jo")); break; case 'u': fmt = UNSIGNED_DECIMAL; field_width = INT_BITS_STRLEN_BOUND (CHAR_BIT * size); sprintf (tspec->fmt_string, "%%*%s", - ISPEC_TO_FORMAT (size_spec, "u", "lu", "llu", "ju")); + ispec_to_format (size_spec, "u", "lu", "llu", "ju")); break; case 'x': fmt = HEXADECIMAL; field_width = (CHAR_BIT * size + 3) / 4; sprintf (tspec->fmt_string, "%%*.%d%s", field_width, - ISPEC_TO_FORMAT (size_spec, "x", "lx", "llx", "jx")); + ispec_to_format (size_spec, "x", "lx", "llx", "jx")); break; default: @@ -801,14 +810,18 @@ decode_one_format (char const *s_orig, char const *s, char const **next, /* Prefer INT, prefer LONG to longer types, and prefer INTMAX to LONG_LONG. */ print_function - = (size_spec == INT ? print_int - : size_spec == SHORT ? (fmt == SIGNED_DECIMAL - ? print_s_short : print_short) - : size_spec == CHAR ? (fmt == SIGNED_DECIMAL - ? print_s_char : print_char) - : size_spec == LONG ? print_long - : size_spec == INTMAX ? print_intmax - : size_spec == LONG_LONG ? print_long_long + = (size_spec == INT + ? print_int + : SHORT < INT && size_spec == SHORT + ? (fmt == SIGNED_DECIMAL ? print_s_short : print_short) + : CHAR < SHORT && size_spec == CHAR + ? (fmt == SIGNED_DECIMAL ? print_s_char : print_char) + : INT < LONG && size_spec == LONG + ? print_long + : LONG < INTMAX && size_spec == INTMAX + ? print_intmax + : LONG < LONG_LONG && LONG_LONG < INTMAX && size_spec == LONG_LONG + ? print_long_long : (affirm (false), nullptr)); break; @@ -892,18 +905,19 @@ decode_one_format (char const *s_orig, char const *s, char const **next, print_function = print_double; field_width = DBL_STRLEN_BOUND_L (decimal_point_len); } - else if (size_spec == FLOAT_SINGLE) + else if (FLOAT_SINGLE < FLOAT_DOUBLE && size_spec == FLOAT_SINGLE) { print_function = print_float; field_width = FLT_STRLEN_BOUND_L (decimal_point_len); } - else if (size_spec == FLOAT_HALF) + else if (FLOAT_HALF < FLOAT_SINGLE && size_spec == FLOAT_HALF) { print_function = fmt == BFLOATING_POINT ? print_bfloat : print_halffloat; field_width = FLT_STRLEN_BOUND_L (decimal_point_len); } - else if (size_spec == FLOAT_LONG_DOUBLE) + else if (FLOAT_DOUBLE < FLOAT_LONG_DOUBLE + && size_spec == FLOAT_LONG_DOUBLE) { print_function = print_long_double; field_width = LDBL_STRLEN_BOUND_L (decimal_point_len); -- 2.48.1