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sysctl: Fix data races in proc_douintvec().

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[ Upstream commit 4762b532ec ]

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

Fixes: e7d316a02f ("sysctl: handle error writing UINT_MAX to u32 fields")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Kuniyuki Iwashima 2022-07-06 16:39:53 -07:00 • committed by Greg Kroah-Hartman
commit d5d54714e3
1 changed files with 2 additions and 2 deletions
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4
kernel/sysctl.c
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@ -583,9 +583,9 @@ static int do_proc_douintvec_conv(unsigned long *lvalp,
if (write) {
if (*lvalp > UINT_MAX)
return -EINVAL;
*valp = *lvalp;
WRITE_ONCE(*valp, *lvalp);
} else {
unsigned int val = *valp;
unsigned int val = READ_ONCE(*valp);
*lvalp = (unsigned long)val;
}
return 0;