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From:   starmiku1207184332@gmail.com
To:     dmitry.torokhov@gmail.com, rydberg@bitmath.org
Cc:     linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
        Teng Qi <starmiku1207184332@gmail.com>
Subject: [PATCH] drivers: input: input: Fix possible sleep-in-atomic bug in input_alloc_absinfo()
Date:   Tue, 25 Apr 2023 07:49:51 +0000
Message-Id: <20230425074951.1042694-1-starmiku1207184332@gmail.com>
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From: Teng Qi <starmiku1207184332@gmail.com>

input_alloc_absinfo() may cause the kernel to sleep by calling kcalloc() with
the GFP_KERNEL flag. It may be called by input_event() holding spinlock through
the following call path: 

input_event(), 433
input_handle_event(), 399
input_get_disposition(), 294
input_handle_abs_event(), 232
input_abs_set_val(), Clang suggests it calls input_alloc_absinfo()
	unconditionally
input_alloc_absinfo(), 483
kcalloc(..., GFP_KERNEL)

This call path can potentially trigger a sleep-in-atomic bug. To prevent this
potential bug, we modify input_alloc_absinfo() to use the GFP_ATOMIC flag
instead of the GFP_KERNEL flag.
The possible bug is detected by a static code analysis tool.

Signed-off-by: Teng Qi <starmiku1207184332@gmail.com>
---
 drivers/input/input.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/input/input.c b/drivers/input/input.c
index 37e876d45eb9..eefc4c85a693 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -480,7 +480,7 @@ void input_alloc_absinfo(struct input_dev *dev)
 	if (dev->absinfo)
 		return;
 
-	dev->absinfo = kcalloc(ABS_CNT, sizeof(*dev->absinfo), GFP_KERNEL);
+	dev->absinfo = kcalloc(ABS_CNT, sizeof(*dev->absinfo), GFP_ATOMIC);
 	if (!dev->absinfo) {
 		dev_err(dev->dev.parent ?: &dev->dev,
 			"%s: unable to allocate memory\n", __func__);
-- 
2.25.1