Hi,every one.
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 <[EMAIL PROTECTED]>
---
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 c8a9d13..5d5926f 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -342,15 +342,13 @@ void clocksource_change_rating(struct clocksource *cs,
int rating)
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;
}
/**
@@ -418,17 +416,20 @@ 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;
}
/*
--
1.5.3
-
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