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| author | Miao Xie <miaox@cn.fujitsu.com> | 2008-02-06 12:36:53 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2008-02-06 21:41:03 +0300 |
| commit | 5e2cb1018a8a583b83d56c80f46507da6f3f2b57 (patch) | |
| tree | b9cbe718649c8be6e2d54aedcf75244fbe56bddd /kernel/time | |
| parent | be6c28e62e3a304b74013afab029af2021e1f50d (diff) | |
| download | linux-5e2cb1018a8a583b83d56c80f46507da6f3f2b57.tar.xz | |
time: fix sysfs_show_{available,current}_clocksources() buffer overflow problem
I found that there is a buffer overflow problem in the following code.
Version: 2.6.24-rc2,
File: kernel/time/clocksource.c:417-432
--------------------------------------------------------------------
static ssize_t
sysfs_show_available_clocksources(struct sys_device *dev, char *buf)
{
struct clocksource *src;
char *curr = buf;
spin_lock_irq(&clocksource_lock);
list_for_each_entry(src, &clocksource_list, list) {
curr += sprintf(curr, "%s ", src->name);
}
spin_unlock_irq(&clocksource_lock);
curr += sprintf(curr, "\n");
return curr - buf;
}
-----------------------------------------------------------------------
sysfs_show_current_clocksources() also has the same problem though in practice
the size of current clocksource's name won't exceed PAGE_SIZE.
I fix the bug by using snprintf according to the specification of the kernel
(Version:2.6.24-rc2,File:Documentation/filesystems/sysfs.txt)
Fix sysfs_show_available_clocksources() and sysfs_show_current_clocksources()
buffer overflow problem with snprintf().
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/time')
| -rw-r--r-- | kernel/time/clocksource.c | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 6e9259a5d501..81afb3927ecc 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -363,15 +363,13 @@ void clocksource_unregister(struct clocksource *cs) static ssize_t sysfs_show_current_clocksources(struct sys_device *dev, char *buf) { - char *curr = buf; + ssize_t count = 0; spin_lock_irq(&clocksource_lock); - curr += sprintf(curr, "%s ", curr_clocksource->name); + count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name); spin_unlock_irq(&clocksource_lock); - curr += sprintf(curr, "\n"); - - return curr - buf; + return count; } /** @@ -439,17 +437,20 @@ static ssize_t sysfs_show_available_clocksources(struct sys_device *dev, char *buf) { struct clocksource *src; - char *curr = buf; + ssize_t count = 0; spin_lock_irq(&clocksource_lock); list_for_each_entry(src, &clocksource_list, list) { - curr += sprintf(curr, "%s ", src->name); + count += snprintf(buf + count, + max((ssize_t)PAGE_SIZE - count, (ssize_t)0), + "%s ", src->name); } spin_unlock_irq(&clocksource_lock); - curr += sprintf(curr, "\n"); + count += snprintf(buf + count, + max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n"); - return curr - buf; + return count; } /* |