[PATCH 4.14 052/237] media: sti: bdisp: fix a possible sleep-in-atomic-context bug in bdisp_device_run()

Greg Kroah-Hartman
2020-02-27T13:54:23Z

From: Jia-Ju Bai <baijiaju1990@gmail.com>

[ Upstream commit bb6d42061a05d71dd73f620582d9e09c8fbf7f5b ]

The driver may sleep while holding a spinlock.
The function call path (from bottom to top) in Linux 4.19 is:

drivers/media/platform/sti/bdisp/bdisp-hw.c, 385:
msleep in bdisp_hw_reset
drivers/media/platform/sti/bdisp/bdisp-v4l2.c, 341:
bdisp_hw_reset in bdisp_device_run
drivers/media/platform/sti/bdisp/bdisp-v4l2.c, 317:
_raw_spin_lock_irqsave in bdisp_device_run

To fix this bug, msleep() is replaced with udelay().

This bug is found by a static analysis tool STCheck written by myself.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Reviewed-by: Fabien Dessenne <fabien.dessenne@st.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/media/platform/sti/bdisp/bdisp-hw.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/media/platform/sti/bdisp/bdisp-hw.c b/drivers/media/platform/sti/bdisp/bdisp-hw.c
index b7892f3efd988..5c4c3f0c57be1 100644
--- a/drivers/media/platform/sti/bdisp/bdisp-hw.c
+++ b/drivers/media/platform/sti/bdisp/bdisp-hw.c
@@ -14,8 +14,8 @@
#define MAX_SRC_WIDTH 2048

/* Reset & boot poll config */
-#define POLL_RST_MAX 50
-#define POLL_RST_DELAY_MS 20
+#define POLL_RST_MAX 500
+#define POLL_RST_DELAY_MS 2

enum bdisp_target_plan {
BDISP_RGB,
@@ -382,7 +382,7 @@ int bdisp_hw_reset(struct bdisp_dev *bdisp)
for (i = 0; i < POLL_RST_MAX; i++) {
if (readl(bdisp->regs + BLT_STA1) & BLT_STA1_IDLE)
break;
- msleep(POLL_RST_DELAY_MS);
+ udelay(POLL_RST_DELAY_MS * 1000);
}
if (i == POLL_RST_MAX)
dev_err(bdisp->dev, "Reset timeout\n");
--
2.20.1