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sysctl: Fix data-races in proc_dointvec_ms_jiffies().

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[ Upstream commit 7d1025e559 ]

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

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
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
2022-07-11 17:15:20 -07:00
committed by Greg Kroah-Hartman
parent 2744e302e7
commit b8871d9186
1 changed files with 4 additions and 4 deletions
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8
kernel/sysctl.c
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@@ -1327,9 +1327,9 @@ static int do_proc_dointvec_ms_jiffies_conv(bool *negp, unsigned long *lvalp,
if (jif > INT_MAX) if (jif > INT_MAX)
return 1; return 1;
*valp = (int)jif; WRITE_ONCE(*valp, (int)jif);
} else { } else {
int val = *valp; int val = READ_ONCE(*valp);
unsigned long lval; unsigned long lval;
if (val < 0) { if (val < 0) {
*negp = true; *negp = true;
@@ -1397,8 +1397,8 @@ int proc_dointvec_userhz_jiffies(struct ctl_table *table, int write,
* @ppos: the current position in the file * @ppos: the current position in the file
* *
* Reads/writes up to table->maxlen/sizeof(unsigned int) integer * Reads/writes up to table->maxlen/sizeof(unsigned int) integer
* values from/to the user buffer, treated as an ASCII string. * values from/to the user buffer, treated as an ASCII string.
* The values read are assumed to be in 1/1000 seconds, and * The values read are assumed to be in 1/1000 seconds, and
* are converted into jiffies. * are converted into jiffies.
* *
* Returns 0 on success. * Returns 0 on success.