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authorYanfei Xu <yanfei.xu@windriver.com>2021-06-28 19:35:01 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-06-29 10:53:47 -0700
commit54dd200c5a251b5db9f6f0f72a251c28e0d7da43 (patch)
tree898026c6323e8fad852160d8944f15097f2ef38e
parent65ebdeef103fd70988fdd0ffef1d4fecb0cb97ed (diff)
mm/kmemleak: fix possible wrong memory scanning period
This commit contains 3 modifications: 1. Convert the type of jiffies_scan_wait to "unsigned long". 2. Use READ/WRITE_ONCE() for accessing "jiffies_scan_wait". 3. Fix the possible wrong memory scanning period. If you set a large memory scanning period like blow, then the "secs" variable will be non-zero, however the value of "jiffies_scan_wait" will be zero. echo "scan=0x10000000" > /sys/kernel/debug/kmemleak It is because the type of the msecs_to_jiffies()'s parameter is "unsigned int", and the "secs * 1000" is larger than its max value. This in turn leads a unexpected jiffies_scan_wait, maybe zero. We corret it by replacing kstrtoul() with kstrtouint(), and check the msecs to prevent it larger than UINT_MAX. Link: https://lkml.kernel.org/r/20210613174022.23044-1-yanfei.xu@windriver.com Signed-off-by: Yanfei Xu <yanfei.xu@windriver.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/kmemleak.c18
1 files changed, 12 insertions, 6 deletions
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 92a2d4885808..228a2fbe0657 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -219,7 +219,7 @@ static struct task_struct *scan_thread;
static unsigned long jiffies_min_age;
static unsigned long jiffies_last_scan;
/* delay between automatic memory scannings */
-static signed long jiffies_scan_wait;
+static unsigned long jiffies_scan_wait;
/* enables or disables the task stacks scanning */
static int kmemleak_stack_scan = 1;
/* protects the memory scanning, parameters and debug/kmemleak file access */
@@ -1567,7 +1567,7 @@ static int kmemleak_scan_thread(void *arg)
}
while (!kthread_should_stop()) {
- signed long timeout = jiffies_scan_wait;
+ signed long timeout = READ_ONCE(jiffies_scan_wait);
mutex_lock(&scan_mutex);
kmemleak_scan();
@@ -1807,14 +1807,20 @@ static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
else if (strncmp(buf, "scan=off", 8) == 0)
stop_scan_thread();
else if (strncmp(buf, "scan=", 5) == 0) {
- unsigned long secs;
+ unsigned secs;
+ unsigned long msecs;
- ret = kstrtoul(buf + 5, 0, &secs);
+ ret = kstrtouint(buf + 5, 0, &secs);
if (ret < 0)
goto out;
+
+ msecs = secs * MSEC_PER_SEC;
+ if (msecs > UINT_MAX)
+ msecs = UINT_MAX;
+
stop_scan_thread();
- if (secs) {
- jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
+ if (msecs) {
+ WRITE_ONCE(jiffies_scan_wait, msecs_to_jiffies(msecs));
start_scan_thread();
}
} else if (strncmp(buf, "scan", 4) == 0)