[PATCH 5.10 073/161] regmap: Fix race condition in hwspinlock irqsave routine

Greg Kroah-Hartman
2026-02-04T14:46:25Z

From: Cheng-Yu Lee <cylee12@realtek.com>

[ Upstream commit 4b58aac989c1e3fafb1c68a733811859df388250 ]

Previously, the address of the shared member '&map->spinlock_flags' was
passed directly to 'hwspin_lock_timeout_irqsave'. This creates a race
condition where multiple contexts contending for the lock could overwrite
the shared flags variable, potentially corrupting the state for the
current lock owner.

Fix this by using a local stack variable 'flags' to store the IRQ state
temporarily.

Fixes: 8698b9364710 ("regmap: Add hardware spinlock support")
Signed-off-by: Cheng-Yu Lee <cylee12@realtek.com>
Co-developed-by: Yu-Chun Lin <eleanor.lin@realtek.com>
Signed-off-by: Yu-Chun Lin <eleanor.lin@realtek.com>
Link: https://patch.msgid.link/20260109032633.8732-1-eleanor.lin@realtek.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/base/regmap/regmap.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 02c21fce457c1..e86d069894c06 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -463,9 +463,11 @@ static void regmap_lock_hwlock_irq(void *__map)
static void regmap_lock_hwlock_irqsave(void *__map)
{
struct regmap *map = __map;
+ unsigned long flags = 0;

hwspin_lock_timeout_irqsave(map->hwlock, UINT_MAX,
- &map->spinlock_flags);
+ &flags);
+ map->spinlock_flags = flags;
}

static void regmap_unlock_hwlock(void *__map)
--
2.51.0