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authorMiao Xie <miaox@cn.fujitsu.com>2008-02-06 12:36:53 +0300
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-06 21:41:03 +0300
commit5e2cb1018a8a583b83d56c80f46507da6f3f2b57 (patch)
treeb9cbe718649c8be6e2d54aedcf75244fbe56bddd /kernel
parentbe6c28e62e3a304b74013afab029af2021e1f50d (diff)
downloadlinux-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')
-rw-r--r--kernel/time/clocksource.c19
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;
}
/*