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tcp: annotate data-race around tcp_md5sig_pool_populated

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[ Upstream commit aacd467c0a576e5e44d2de4205855dc0fe43f6fb ]

tcp_md5sig_pool_populated can be read while another thread
changes its value.

The race has no consequence because allocations
are protected with tcp_md5sig_mutex.

This patch adds READ_ONCE() and WRITE_ONCE() to document
the race and silence KCSAN.

Reported-by: Abhishek Shah <abhishek.shah@columbia.edu>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Eric Dumazet
2022-08-22 21:15:28 +00:00
committed by Greg Kroah-Hartman
parent 129ca0db95
commit 0958e487e8
1 changed files with 10 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
net/ipv4/tcp.c
View File

@@ -4043,12 +4043,16 @@ static void __tcp_alloc_md5sig_pool(void)
* to memory. See smp_rmb() in tcp_get_md5sig_pool() * to memory. See smp_rmb() in tcp_get_md5sig_pool()
*/ */
smp_wmb(); smp_wmb();
tcp_md5sig_pool_populated = true; /* Paired with READ_ONCE() from tcp_alloc_md5sig_pool()
* and tcp_get_md5sig_pool().
*/
WRITE_ONCE(tcp_md5sig_pool_populated, true);
} }
bool tcp_alloc_md5sig_pool(void) bool tcp_alloc_md5sig_pool(void)
{ {
if (unlikely(!tcp_md5sig_pool_populated)) { /* Paired with WRITE_ONCE() from __tcp_alloc_md5sig_pool() */
if (unlikely(!READ_ONCE(tcp_md5sig_pool_populated))) {
mutex_lock(&tcp_md5sig_mutex); mutex_lock(&tcp_md5sig_mutex);
if (!tcp_md5sig_pool_populated) { if (!tcp_md5sig_pool_populated) {
@@ -4059,7 +4063,8 @@ bool tcp_alloc_md5sig_pool(void)
mutex_unlock(&tcp_md5sig_mutex); mutex_unlock(&tcp_md5sig_mutex);
} }
return tcp_md5sig_pool_populated; /* Paired with WRITE_ONCE() from __tcp_alloc_md5sig_pool() */
return READ_ONCE(tcp_md5sig_pool_populated);
} }
EXPORT_SYMBOL(tcp_alloc_md5sig_pool); EXPORT_SYMBOL(tcp_alloc_md5sig_pool);
@@ -4075,7 +4080,8 @@ struct tcp_md5sig_pool *tcp_get_md5sig_pool(void)
{ {
local_bh_disable(); local_bh_disable();
if (tcp_md5sig_pool_populated) { /* Paired with WRITE_ONCE() from __tcp_alloc_md5sig_pool() */
if (READ_ONCE(tcp_md5sig_pool_populated)) {
/* coupled with smp_wmb() in __tcp_alloc_md5sig_pool() */ /* coupled with smp_wmb() in __tcp_alloc_md5sig_pool() */
smp_rmb(); smp_rmb();
return this_cpu_ptr(&tcp_md5sig_pool); return this_cpu_ptr(&tcp_md5sig_pool);