[PATCH] staging: lustre: lustre: obdclass: lprocfs_status.c: Fix for possible null pointer dereference
9:52 a.m.
There is otherwise a risk of a possible null pointer dereference.
Was largely found by using a static code analysis program called cppcheck.
Signed-off-by: Rickard Strandqvist <rickard_strandqvist(a)spectrumdigital.se>
---
.../lustre/lustre/obdclass/lprocfs_status.c | 24 +++++++++++---------
1 file changed, 13 insertions(+), 11 deletions(-)
diff --git a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
index 61e04af..5227324 100644
--- a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
+++ b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
@@ -1897,17 +1897,19 @@ int lprocfs_write_frac_u64_helper(const char *buffer, unsigned
long count,
}
units = 1;
- switch (*end) {
- case 'p': case 'P':
- units <<= 10;
- case 't': case 'T':
- units <<= 10;
- case 'g': case 'G':
- units <<= 10;
- case 'm': case 'M':
- units <<= 10;
- case 'k': case 'K':
- units <<= 10;
+ if (end) {
+ switch (*end) {
+ case 'p': case 'P':
+ units <<= 10;
+ case 't': case 'T':
+ units <<= 10;
+ case 'g': case 'G':
+ units <<= 10;
+ case 'm': case 'M':
+ units <<= 10;
+ case 'k': case 'K':
+ units <<= 10;
+ }
}
/* Specified units override the multiplier */
if (units)
--
1.7.10.4
12:51 p.m.
On Sun, 2014-12-14 at 23:52 +0100, Rickard Strandqvist wrote:
There is otherwise a risk of a possible null pointer dereference.
Was largely found by using a static code analysis program called cppcheck.
Perhaps the tool could use a little work.
It's not possible for end to be NULL no?
unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
{
unsigned long long result;
unsigned int rv;
cp = _parse_integer_fixup_radix(cp, &base);
rv = _parse_integer(cp, base, &result);
/* FIXME */
cp += (rv & ~KSTRTOX_OVERFLOW);
if (endp)
*endp = (char *)cp;
return result;
}
EXPORT_SYMBOL(simple_strtoull);
diff --git a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
[]
Above this:
whole = simple_strtoull(pbuf, &end, 10);
+++ b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
@@ -1897,17 +1897,19 @@ int lprocfs_write_frac_u64_helper(const char *buffer, unsigned
long count,
}
units = 1;
- switch (*end) {
- case 'p': case 'P':
- units <<= 10;
- case 't': case 'T':
- units <<= 10;
- case 'g': case 'G':
- units <<= 10;
- case 'm': case 'M':
- units <<= 10;
- case 'k': case 'K':
- units <<= 10;
+ if (end) {
+ switch (*end) {
+ case 'p': case 'P':
+ units <<= 10;
+ case 't': case 'T':
+ units <<= 10;
+ case 'g': case 'G':
+ units <<= 10;
+ case 'm': case 'M':
+ units <<= 10;
+ case 'k': case 'K':
+ units <<= 10;
+ }
The only thing I might do is
switch (tolower(*end)) {
and remove the second case entry for each line
9:23 a.m.
Hi Joe
No, it does not look like end can be NULL then.
Then remove the end != NULL instead?
...
if (end != NULL && *end == '.') {
However, I am hesitant to the tolower() I think double case is faster...?
Kind regards
Rickard Strandqvist
2014-12-15 2:51 GMT+01:00 Joe Perches <joe(a)perches.com>:
On Sun, 2014-12-14 at 23:52 +0100, Rickard Strandqvist wrote:
> There is otherwise a risk of a possible null pointer dereference.
>
> Was largely found by using a static code analysis program called cppcheck.
Perhaps the tool could use a little work.
It's not possible for end to be NULL no?
unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
{
unsigned long long result;
unsigned int rv;
cp = _parse_integer_fixup_radix(cp, &base);
rv = _parse_integer(cp, base, &result);
/* FIXME */
cp += (rv & ~KSTRTOX_OVERFLOW);
if (endp)
*endp = (char *)cp;
return result;
}
EXPORT_SYMBOL(simple_strtoull);
> diff --git a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
[]
Above this:
whole = simple_strtoull(pbuf, &end, 10);
> +++ b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
> @@ -1897,17 +1897,19 @@ int lprocfs_write_frac_u64_helper(const char *buffer,
unsigned long count,
> }
>
> units = 1;
> - switch (*end) {
> - case 'p': case 'P':
> - units <<= 10;
> - case 't': case 'T':
> - units <<= 10;
> - case 'g': case 'G':
> - units <<= 10;
> - case 'm': case 'M':
> - units <<= 10;
> - case 'k': case 'K':
> - units <<= 10;
> + if (end) {
> + switch (*end) {
> + case 'p': case 'P':
> + units <<= 10;
> + case 't': case 'T':
> + units <<= 10;
> + case 'g': case 'G':
> + units <<= 10;
> + case 'm': case 'M':
> + units <<= 10;
> + case 'k': case 'K':
> + units <<= 10;
> + }
The only thing I might do is
switch (tolower(*end)) {
and remove the second case entry for each line
10:53 a.m.
On Mon, 2014-12-15 at 23:23 +0100, Rickard Strandqvist wrote:
Hi Joe
Hello Rickard
No, it does not look like end can be NULL then.
Then remove the end != NULL instead?
...
if (end != NULL && *end == '.') {
Up to you.
However, I am hesitant to the tolower() I think double case is
faster...?
I doubt code execution speed is paramount here.
Maybe see if the object code size is smaller one
way or the other.
2:08 p.m.
Strongly agreed that execution speed is not critical here. It's the update of a proc
variable, not a tight loop or critical section.
Normally I'd leave it alone, but since you're writing a patch anyway, I'd do
'tolower' myself. I dislike the stacked case statements on a single line like
that. (It's the only time I've seen them written that way. Perhaps it's
common and I've just missed it.)
Regards,
- Patrick
________________________________________
From: HPDD-discuss [hpdd-discuss-bounces(a)lists.01.org] on behalf of Joe Perches
[joe(a)perches.com]
Sent: Monday, December 15, 2014 5:53 PM
To: Rickard Strandqvist
Cc: devel(a)driverdev.osuosl.org; Fabian Frederick; Julia Lawall; James Simmons; Greg
Kroah-Hartman; linux-kernel(a)vger.kernel.org; Greg Donald; HPDD-discuss(a)lists.01.org;
Andriy Skulysh
Subject: Re: [HPDD-discuss] [PATCH] staging: lustre: lustre: obdclass: lprocfs_status.c:
Fix for possible null pointer dereference
On Mon, 2014-12-15 at 23:23 +0100, Rickard Strandqvist wrote:
Hi Joe
Hello Rickard
No, it does not look like end can be NULL then.
Then remove the end != NULL instead?
...
if (end != NULL && *end == '.') {
Up to you.
However, I am hesitant to the tolower() I think double case is
faster...?
I doubt code execution speed is paramount here.
Maybe see if the object code size is smaller one
way or the other.
_______________________________________________
HPDD-discuss mailing list
HPDD-discuss(a)lists.01.org
https://lists.01.org/mailman/listinfo/hpdd-discuss
3:40 p.m.
On Sun, Dec 14, 2014 at 4:52 PM, Rickard Strandqvist
<rickard_strandqvist(a)spectrumdigital.se> wrote:
units = 1;
...
/* Specified units override the multiplier */
if (units)
That doesn't make much sense. The conditional logic will always be
executed. Maybe this is what's intended?
/* Specified units override the multiplier */
- if (units)
+ if (units > 1)
mult = mult < 0 ? -units : units;
Chris
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Rickard Strandqvist