From: Xiaotian Feng <dfeng@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
Oleg Nesterov <oleg@redhat.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Neil Horman <nhorman@tuxdriver.com>,
Roland McGrath <roland@redhat.com>
Subject: Re: [RFC PATCH v3] core_pattern: fix long parameters was truncated by core_pattern handler
Date: Tue, 24 Aug 2010 14:18:32 +0800 [thread overview]
Message-ID: <4C736438.8010206@redhat.com> (raw)
In-Reply-To: <20100823141843.f177bf1f.akpm@linux-foundation.org>
On 08/24/2010 05:18 AM, Andrew Morton wrote:
> On Fri, 20 Aug 2010 17:35:58 +0800
> Xiaotian Feng<dfeng@redhat.com> wrote:
>
>> We met a parameter truncated issue, consider following:
>>> echo "|/root/core_pattern_pipe_test %p /usr/libexec/blah-blah-blah \
>> %s %c %p %u %g 11 12345678901234567890123456789012345678 %t"> \
>> /proc/sys/kernel/core_pattern
>>
>> This is okay because the strings is less than CORENAME_MAX_SIZE.
>> "cat /proc/sys/kernel/core_pattern" shows the whole string. but
>> after we run core_pattern_pipe_test in man page, we found last
>> parameter was truncated like below:
>> argc[10]=<12807486>
>>
>> The root cause is core_pattern allows % specifiers, which need to be
>> replaced during parse time, but the replace may expand the strings
>> to larger than CORENAME_MAX_SIZE. So if the last parameter is %
>> specifiers, the replace code is using snprintf(out_ptr, out_end - out_ptr, ...),
>> this will write out of corename array.
>>
>> Changes since v2:
>> Introduced generic function cn_printf and make format_corename remember the time
>> has been expanded.
>>
>> Changes since v1:
>> This patch allocates corename at runtime, if the replace doesn't have enough
>> memory, expand the corename dynamically.
>
>
>> + if (cn->used == cn->size)
>> + if (expand_corename(cn))
>> + goto out_fail;
>> +
>> + out_ptr = cn->corename + cn->used;
>> + *out_ptr = *pat_ptr++;
>> + cn->used++;
>
>
>> - if (out_ptr == out_end)
>> - goto out;
>> - *out_ptr++ = '%';
>> + if (cn->used == cn->size)
>> + if (expand_corename(cn))
>> + goto out_fail;
>> +
>> + out_ptr = cn->corename + cn->used;
>> + *out_ptr = '%';
>> + cn->used++;
>
>
>> + out_ptr = cn->corename + cn->used;
>> + if (cn->used == cn->size)
>> + if (expand_corename(cn))
>> + goto out_fail;
>> +
>> + out_ptr = cn->corename + cn->used;
>> *out_ptr = 0;
>
> Quite a bit of code duplication there. A little helper function which
> adds a single char to the output would tidy that up.
Yep, this would be much more cleaner ;-)
>
> However I think that if the % and %% handers are converted to call
> cn_printf() then the output is always null-terninated and the third
> hunk of code above simply becomes unneeded?
You are absolutely right ;-)
>
> Something like this, although I didn't try very hard. Just a
> suggestion to work with ;)
>
Yep, we just need change a little on your patch
- err = cn_printf(cn, "%%");
+ err = cn_printf(cn, "%");
Do you need me to resend a v4 patch?
next prev parent reply other threads:[~2010-08-24 6:18 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-29 12:42 [RFC PATCH] core_pattern: fix long parameters was truncated by core_pattern handler Xiaotian Feng
2010-07-29 13:31 ` Neil Horman
2010-08-02 12:23 ` [RFC PATCH V2] " Xiaotian Feng
2010-08-02 13:50 ` Oleg Nesterov
2010-08-03 10:59 ` Neil Horman
2010-08-20 9:22 ` [RFC PATCH v3] " Xiaotian Feng
2010-08-20 9:35 ` Xiaotian Feng
2010-08-20 9:35 ` Xiaotian Feng
2010-08-23 11:07 ` Neil Horman
2010-08-23 23:02 ` KOSAKI Motohiro
2010-08-23 21:18 ` Andrew Morton
2010-08-24 6:18 ` Xiaotian Feng [this message]
2010-08-24 6:28 ` Andrew Morton
2010-08-24 9:42 ` [PATCH v4] " Xiaotian Feng
2010-08-24 22:47 ` Andrew Morton
2010-08-25 1:58 ` Xiaotian Feng
2010-08-25 2:17 ` [PATCH v5] " Xiaotian Feng
2010-08-02 14:30 ` [RFC PATCH V2] " Denys Vlasenko
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