@@ -85,6 +85,7 @@ PROC_HANDLER(proc_do_static_key);
PROC_HANDLER(proc_dobool_lockless);
PROC_HANDLER(proc_dointvec_lockless);
+PROC_HANDLER(proc_douintvec_lockless);
/*
* Register a set of sysctl names by calling register_sysctl_table
@@ -474,9 +474,11 @@ 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;
@@ -775,7 +777,7 @@ static int proc_dointvec_minmax_warn_RT_change(struct ctl_table *table,
#endif
/**
- * proc_douintvec - read a vector of unsigned integers
+ * proc_douintvec_lockless - read/write a vector of unsigned integers locklessly
* @table: the sysctl table
* @write: %TRUE if this is a write to the sysctl file
* @buffer: the user buffer
@@ -787,13 +789,19 @@ static int proc_dointvec_minmax_warn_RT_change(struct ctl_table *table,
*
* Returns 0 on success.
*/
-int proc_douintvec(struct ctl_table *table, int write, void *buffer,
- size_t *lenp, loff_t *ppos)
+int proc_douintvec_lockless(struct ctl_table *table, int write, void *buffer,
+ size_t *lenp, loff_t *ppos)
{
return do_proc_douintvec(table, write, buffer, lenp, ppos,
do_proc_douintvec_conv, NULL);
}
+int proc_douintvec(struct ctl_table *table, int write, void *buffer,
+ size_t *lenp, loff_t *ppos)
+{
+ return proc_douintvec_lockless(table, write, buffer, lenp, ppos);
+}
+
/*
* Taint values can only be increased
* This means we can safely use a temporary.
@@ -1513,6 +1521,7 @@ PROC_HANDLER_ENOSYS(proc_do_large_bitmap);
PROC_HANDLER_ENOSYS(proc_dobool_lockless);
PROC_HANDLER_ENOSYS(proc_dointvec_lockless);
+PROC_HANDLER_ENOSYS(proc_douintvec_lockless);
#endif /* CONFIG_PROC_SYSCTL */
@@ -2425,3 +2434,4 @@ EXPORT_SYMBOL(proc_do_large_bitmap);
EXPORT_SYMBOL(proc_dobool_lockless);
EXPORT_SYMBOL(proc_dointvec_lockless);
+EXPORT_SYMBOL(proc_douintvec_lockless);
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()/WRITE_ONCE() internally to fix a data-race 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. In case we miss such fixes, this patch converts proc_douintvec() to a wrapper of proc_douintvec_lockless(). When we fix a data-race in the other subsystem, we can explicitly set it as a handler. Also, this patch removes proc_douintvec()'s document and adds proc_douintvec_lockless()'s one so that no one will use proc_douintvec() anymore. Fixes: e7d316a02f68 ("sysctl: handle error writing UINT_MAX to u32 fields") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> --- CC: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org> --- include/linux/sysctl.h | 1 + kernel/sysctl.c | 20 +++++++++++++++----- 2 files changed, 16 insertions(+), 5 deletions(-)