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authorKuniyuki Iwashima <kuniyu@amazon.com>2022-07-06 16:39:57 -0700
committerDavid S. Miller <davem@davemloft.net>2022-07-08 12:10:33 +0100
commite877820877663fbae8cb9582ea597a7230b94df3 (patch)
tree9aec0e9f7112b4051872d82b5c19f74af8c62f4d /kernel/sysctl.c
parentc31bcc8fb89fc2812663900589c6325ba35d9a65 (diff)
sysctl: Fix data races in proc_dointvec_jiffies().
A sysctl variable is accessed concurrently, and there is always a chance of data-race. So, all readers and writers need some basic protection to avoid load/store-tearing. This patch changes proc_dointvec_jiffies() to use READ_ONCE() and WRITE_ONCE() internally to fix data-races on the sysctl side. For now, proc_dointvec_jiffies() itself is tolerant to a data-race, but we still need to add annotations on the other subsystem's side. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/sysctl.c')
-rw-r--r--kernel/sysctl.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 8c55ba01f41b..bf9383d17e1b 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1173,9 +1173,12 @@ static int do_proc_dointvec_jiffies_conv(bool *negp, unsigned long *lvalp,
if (write) {
if (*lvalp > INT_MAX / HZ)
return 1;
- *valp = *negp ? -(*lvalp*HZ) : (*lvalp*HZ);
+ if (*negp)
+ WRITE_ONCE(*valp, -*lvalp * HZ);
+ else
+ WRITE_ONCE(*valp, *lvalp * HZ);
} else {
- int val = *valp;
+ int val = READ_ONCE(*valp);
unsigned long lval;
if (val < 0) {
*negp = true;