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| author | Tom Tromey <tom@tromey.com> | 2018-07-29 20:23:33 -0600 |
|---|---|---|
| committer | Tom Tromey <tom@tromey.com> | 2018-10-03 15:19:06 -0600 |
| commit | 20562150d8a894bc91657c843ee88c508188e32e (patch) | |
| tree | b211b0f74e83b41e417b21e6e9faa905b49acc4e /gdb/c-exp.y | |
| parent | d359392f976d48b04a27e6a09b5b61846b0727f9 (diff) | |
| download | gdb-20562150d8a894bc91657c843ee88c508188e32e.zip gdb-20562150d8a894bc91657c843ee88c508188e32e.tar.gz gdb-20562150d8a894bc91657c843ee88c508188e32e.tar.bz2 | |
Avoid undefined behavior in parse_number
-fsanitize=undefined pointed out that c-exp.y relied on undefined
behavior here:
if (c != 'l' && c != 'u')
n *= base;
...when a large hex constant "just fit" into a LONGEST, causing the
high bit to be set.
This fixes the problem by having the function work in an unsigned
type.
gdb/ChangeLog
2018-10-03 Tom Tromey <tom@tromey.com>
* c-exp.y (parse_number): Work in unsigned. Remove casts.
Diffstat (limited to 'gdb/c-exp.y')
| -rw-r--r-- | gdb/c-exp.y | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/gdb/c-exp.y b/gdb/c-exp.y index 0326ee0..09e31d2 100644 --- a/gdb/c-exp.y +++ b/gdb/c-exp.y @@ -1760,10 +1760,8 @@ static int parse_number (struct parser_state *par_state, const char *buf, int len, int parsed_float, YYSTYPE *putithere) { - /* FIXME: Shouldn't these be unsigned? We don't deal with negative values - here, and we do kind of silly things like cast to unsigned. */ - LONGEST n = 0; - LONGEST prevn = 0; + ULONGEST n = 0; + ULONGEST prevn = 0; ULONGEST un; int i = 0; @@ -1922,7 +1920,7 @@ parse_number (struct parser_state *par_state, on 0x123456789 when LONGEST is 32 bits. */ if (c != 'l' && c != 'u' && n != 0) { - if ((unsigned_p && (ULONGEST) prevn >= (ULONGEST) n)) + if (unsigned_p && prevn >= n) error (_("Numeric constant too large.")); } prevn = n; @@ -1940,7 +1938,7 @@ parse_number (struct parser_state *par_state, the case where it is we just always shift the value more than once, with fewer bits each time. */ - un = (ULONGEST)n >> 2; + un = n >> 2; if (long_p == 0 && (un >> (gdbarch_int_bit (parse_gdbarch (par_state)) - 2)) == 0) { |