Yum Rayan wrote:
On Tue, 29 Mar 2005 09:43:12 -0800, Randy.Dunlap <[email protected]> wrote:
Yum Rayan wrote:
Attempt to reduce stack usage in module.c (linux-2.6.12-rc1-mm3).
Specifically from checkstack.pl
Also while at it, fix following in who_is_doing_it(...)
- use only as much memory is needed
- do not write past array index for the boundary case
I don't see a boundary case problem with the current code,
hence I don't see why the kmalloc(len + 1, GFP_KERNEL) is
needed...
Let's consider the original code and len = 513
1399 static void who_is_doing_it(void)
1400 {
1401 /* Print out all the args. */
1402 char args[512];
1403 unsigned long i, len = current->mm->arg_end -
current->mm->arg_start;
1404
1405 if (len > 512)
1406 len = 512;
1407
1408 len -= copy_from_user(args, (void
*)current->mm->arg_start, len);
1409
1410 for (i = 0; i < len; i++) {
1411 if (args[i] == '\0')
1412 args[i] = ' ';
1413 }
1414 args[i] = 0;
1415 printk("ARGS: %s\n", args);
1416 }
After lines 1410 thru 1413, "i" wil be 512. So line 1414 will be
"args[512] = 0". But args is 512 byte array with last legally
accessible element at 511?
Yes, it's so obvious (now). :)
File names start one level deeper than wanted. They should begin
with linux/ or a/ or ./ e.g.
There are plenty of docs on this, please let me know if you need
references to them.
Point noted. Will post patch to linux/Documentation/SubmittingPatches,
hopefully making it more clear. Reworked patch at end of email.
Good idea, thanks.
--
~Randy
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