lkml.org 
[lkml]   [2021]   [Oct]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2] sched: Fix implicit type conversion
Date
The variable 'n' is defined as ULONG. However in the cpumask_next(),
it is used as INT.
That is vulnerable and may cause overflow.
For example, if the value of 'n' is (2^31 - 1), then it can pass the
check ('n == 0') and ('n-- > 0'). Then in cpumask_next(), its value
is (2^31 - 3). But it is implicit type conversed to int, its actual
value is -3, which is illegal in the cpumask_next().
Therefore, it might be better to define 'n' as INT.

Fixes: cb152ff ("sched: Fix /proc/sched_stat failure on very very large systems")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
---
kernel/sched/stats.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/stats.c b/kernel/sched/stats.c
index 3f93fc3..6503d3a 100644
--- a/kernel/sched/stats.c
+++ b/kernel/sched/stats.c
@@ -82,7 +82,7 @@ static int show_schedstat(struct seq_file *seq, void *v)
*/
static void *schedstat_start(struct seq_file *file, loff_t *offset)
{
- unsigned long n = *offset;
+ int n = *offset;

if (n == 0)
return (void *) 1;
--
2.7.4
\
 
 \ /
  Last update: 2021-10-25 14:21    [W:0.028 / U:0.084 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site