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SubjectRe: [PATCH 1/6] POWERPC: use KSYM_NAME_LEN
Cyrill Gorcunov wrote:
> Use KSYM_NAME_LEN instead of numeric value.

The patch series looks like a nice cleanup, except for a few things in
this patch.

> Actually because of too small 'tmp' there is
> a potential buffer overflow.

I don't think there is. "tmp" is not being passed to kallsyms to be
filled with a symbol name, but it's being used to hold a name written by
the user to lookup an address.

If the powerpc/xmon people feel that 63 characters is enough to hold a
symbol name, it's their problem, but there is no buffer overflow.

> Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
> ---
>
> Index: linux-2.6.git/arch/powerpc/xmon/xmon.c
> ===================================================================
> --- linux-2.6.git.orig/arch/powerpc/xmon/xmon.c 2008-01-23 19:04:42.000000000 +0300
> +++ linux-2.6.git/arch/powerpc/xmon/xmon.c 2008-01-23 19:12:45.000000000 +0300
> @@ -69,7 +69,7 @@ static unsigned long ndump = 64;
> static unsigned long nidump = 16;
> static unsigned long ncsum = 4096;
> static int termch;
> -static char tmpstr[128];
> +static char tmpstr[KSYM_NAME_LEN];

This one seems ok, since "tmpstr" is used everywhere to hold symbol names.

> #define JMP_BUF_LEN 23
> static long bus_error_jmp[JMP_BUF_LEN];
> @@ -2354,7 +2354,7 @@ scanhex(unsigned long *vp)
> }
> } else if (c == '$') {
> int i;
> - for (i=0; i<63; i++) {
> + for (i = 0; i < sizeof(tmpstr) / 2; i++) {

This one is completely out of the blue. Why "sizeof(tmpstr) / 2"?

It would make more sense to use "sizeof(tmpstr) - 1", but either way it
is a change in behavior.

> c = inchar();
> if (isspace(c)) {
> termch = c;
> @@ -2467,7 +2467,7 @@ symbol_lookup(void)
> {
> int type = inchar();
> unsigned long addr;
> - static char tmp[64];
> + static char tmp[KSYM_NAME_LEN];
>
> switch (type) {
> case 'a':
> @@ -2476,7 +2476,7 @@ symbol_lookup(void)
> termch = 0;
> break;
> case 's':
> - getstring(tmp, 64);
> + getstring(tmp, sizeof(tmp));
> if (setjmp(bus_error_jmp) == 0) {
> catch_memory_errors = 1;
> sync();

This also introduces a change in behavior. It is still a nice cleanup,
though. So, if the powerpc people feel they can spare an extra 64 bytes
of stack here, I guess it's ok.

--
Paulo Marques - www.grupopie.com

"As far as we know, our computer has never had an undetected error."
Weisert


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