linux-kernel - [PATCH] sound/pci/riptide or drivers/base/firmware: Fix a possible sleep-in-atomic bug

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Date:   Mon,  9 Oct 2017 10:13:16 +0800
From:   Jia-Ju Bai <baijiaju1990@....com>
To:     mcgrof@...nel.org, gregkh@...uxfoundation.org, perex@...ex.cz,
        tiwai@...e.com, dhowells@...hat.com, bhumirks@...il.com,
        fabf@...net.be
Cc:     alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@....com>
Subject: [PATCH] sound/pci/riptide or drivers/base/firmware: Fix a possible sleep-in-atomic bug

The riptide driver may sleep under a spinlock, and the function call path is:
snd_riptide_prepare (acquire the spinlock)
  setsampleformat
    sendcmd
      riptide_reset
        try_to_load_firmware
          request_firmware
            _request_firmware (drivers/base/firmware_class.c)
              _request_firmware_prepare
                kzalloc(GFP_KERNEL) --> may sleep

To fix it, GFP_KERNEL is replaced with GFP_ATOMIC in _request_firmware_prepare.
This bug is found by my static analysis tool and my code review.

Signed-off-by: Jia-Ju Bai <baijiaju1990@....com>
---
 drivers/base/firmware_class.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 4b57cf5..d89f676 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -1138,7 +1138,7 @@ static inline void kill_pending_fw_fallback_reqs(bool only_kill_custom) { }
 	struct firmware_buf *buf;
 	int ret;
 
-	*firmware_p = firmware = kzalloc(sizeof(*firmware), GFP_KERNEL);
+	*firmware_p = firmware = kzalloc(sizeof(*firmware), GFP_ATOMIC);
 	if (!firmware) {
 		dev_err(device, "%s: kmalloc(struct firmware) failed\n",
 			__func__);
-- 
1.7.9.5