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From: "larue at cadence dot com" <sourceware-bugzilla@sourceware.org> To: gdb-prs@sourceware.org Subject: [Bug gdb/9885] field for register names too narrow Date: Mon, 01 Dec 2014 21:07:00 -0000 [thread overview] Message-ID: <bug-9885-4717-6K1I8xdKTM@http.sourceware.org/bugzilla/> (raw) In-Reply-To: <bug-9885-4717@http.sourceware.org/bugzilla/> https://sourceware.org/bugzilla/show_bug.cgi?id=9885 --- Comment #1 from larue at cadence dot com --- I have recently encountered this problem, and found it is much more severe than indicated in this bug report. If a register name is > 15 characters then a negative value is passed to n_spaces(). This causes garbage to be printed, and occasional crashes of gdb. This problem still exists in gdb-7.8.1. The function default_print_one_register_info() calls: print_spaces_filtered (15 - strlen (name), file); if the register length is greater than 15, then print_spaces_filtered is called with a negative value. The following is a snippet of code from gdb/utils.c. Notice that if n < 0, then n_spaces returns pointer to potentially unallocated data in the heap. This sometimes causes a crash in gdb, and garbage is printed in other cases. char * n_spaces (int n) { char *t; static char *spaces = 0; static int max_spaces = -1; if (n > max_spaces) { if (spaces) xfree (spaces); spaces = (char *) xmalloc (n + 1); for (t = spaces + n; t != spaces;) *--t = ' '; spaces[n] = '\0'; max_spaces = n; } return spaces + max_spaces - n; } void print_spaces_filtered (int n, struct ui_file *stream) { fputs_filtered (n_spaces (n), stream); } Ideally, gdb should be able to nicely print with arbitrary length register names, but at a minimum the crash and garbage output should be fixed. A simple way to do this is to put this check in n_spaces() char * n_spaces (int n) { char *t; static char *spaces = 0; static int max_spaces = -1; if (n > max_spaces) { if (spaces) xfree (spaces); spaces = (char *) xmalloc (n + 1); for (t = spaces + n; t != spaces;) *--t = ' '; spaces[n] = '\0'; max_spaces = n; } return spaces + max_spaces - n; } -- You are receiving this mail because: You are on the CC list for the bug.
next prev parent reply other threads:[~2014-12-01 21:07 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <bug-9885-4717@http.sourceware.org/bugzilla/> 2014-12-01 20:50 ` larue at cadence dot com 2014-12-01 21:07 ` larue at cadence dot com [this message] 2014-12-01 21:12 ` larue at cadence dot com 2020-04-28 16:01 ` ssbssa at sourceware dot org
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