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* [Bug gdb/9885] field for register names too narrow
[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
` (2 subsequent siblings)
3 siblings, 0 replies; 4+ messages in thread
From: larue at cadence dot com @ 2014-12-01 20:50 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=9885
larue at cadence dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |larue at cadence dot com
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* [Bug gdb/9885] field for register names too narrow
[not found] <bug-9885-4717@http.sourceware.org/bugzilla/>
2014-12-01 20:50 ` [Bug gdb/9885] field for register names too narrow larue at cadence dot com
@ 2014-12-01 21:07 ` larue at cadence dot com
2014-12-01 21:12 ` larue at cadence dot com
2020-04-28 16:01 ` ssbssa at sourceware dot org
3 siblings, 0 replies; 4+ messages in thread
From: larue at cadence dot com @ 2014-12-01 21:07 UTC (permalink / raw)
To: gdb-prs
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;
}
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* [Bug gdb/9885] field for register names too narrow
[not found] <bug-9885-4717@http.sourceware.org/bugzilla/>
2014-12-01 20:50 ` [Bug gdb/9885] field for register names too narrow larue at cadence dot com
2014-12-01 21:07 ` larue at cadence dot com
@ 2014-12-01 21:12 ` larue at cadence dot com
2020-04-28 16:01 ` ssbssa at sourceware dot org
3 siblings, 0 replies; 4+ messages in thread
From: larue at cadence dot com @ 2014-12-01 21:12 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=9885
--- Comment #2 from larue at cadence dot com ---
Oops, accidentally saved before pasting in the patch (shown below):
char *
n_spaces (int n)
{
char *t;
static char *spaces = 0;
static int max_spaces = -1;
/* Prevent heap corruption if n is negative (which occurs if
default_print_one_register_info is called with a register whose name
is > 15 characters long */
if (n < 0)
n = 0;
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;
}
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* [Bug gdb/9885] field for register names too narrow
[not found] <bug-9885-4717@http.sourceware.org/bugzilla/>
` (2 preceding siblings ...)
2014-12-01 21:12 ` larue at cadence dot com
@ 2020-04-28 16:01 ` ssbssa at sourceware dot org
3 siblings, 0 replies; 4+ messages in thread
From: ssbssa at sourceware dot org @ 2020-04-28 16:01 UTC (permalink / raw)
To: gdb-prs
https://sourceware.org/bugzilla/show_bug.cgi?id=9885
Hannes Domani <ssbssa at sourceware dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|6.8 |8.2
Status|UNCONFIRMED |RESOLVED
Resolution|--- |FIXED
CC| |ssbssa at sourceware dot org
--- Comment #3 from Hannes Domani <ssbssa at sourceware dot org> ---
Fixed since version 8.2, with this commit:
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=e813d34aaabee0ca034fa5ddd50e76ade80318bc
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[not found] <bug-9885-4717@http.sourceware.org/bugzilla/>
2014-12-01 20:50 ` [Bug gdb/9885] field for register names too narrow larue at cadence dot com
2014-12-01 21:07 ` larue at cadence dot com
2014-12-01 21:12 ` larue at cadence dot com
2020-04-28 16:01 ` ssbssa at sourceware dot org
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