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sysctl: Fix data-races in proc_dou8vec_minmax().

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commit 7dee5d7747a69aa2be41f04c6a7ecfe3ac8cdf18 upstream.

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_dou8vec_minmax() to use READ_ONCE() and
WRITE_ONCE() internally to fix data-races on the sysctl side.  For now,
proc_dou8vec_minmax() itself is tolerant to a data-race, but we still
need to add annotations on the other subsystem's side.

Fixes: cb9444130662 ("sysctl: add proc_dou8vec_minmax()")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kuniyuki Iwashima 2022-07-11 17:15:19 -07:00 committed by Greg Kroah-Hartman
parent 56314b90fd
commit f177b382c3
1 changed files with 2 additions and 2 deletions
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4
kernel/sysctl.c
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@ -1109,13 +1109,13 @@ int proc_dou8vec_minmax(struct ctl_table *table, int write,
tmp.maxlen = sizeof(val);
tmp.data = &val;
val = *data;
val = READ_ONCE(*data);
res = do_proc_douintvec(&tmp, write, buffer, lenp, ppos,
do_proc_douintvec_minmax_conv, &param);
if (res)
return res;
if (write)
*data = val;
WRITE_ONCE(*data, val);
return 0;
}
EXPORT_SYMBOL_GPL(proc_dou8vec_minmax);