netdev - [PATCH v3] mwifiex: fix sleep in atomic context bugs caused by dev

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Date:   Mon, 23 May 2022 13:28:10 +0800
From:   Duoming Zhou <duoming@....edu.cn>
To:     linux-wireless@...r.kernel.org
Cc:     amitkarwar@...il.com, ganapathi017@...il.com,
        sharvari.harisangam@....com, huxinming820@...il.com,
        kvalo@...nel.org, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, gregkh@...uxfoundation.org,
        rafael@...nel.org, Duoming Zhou <duoming@....edu.cn>
Subject: [PATCH v3] mwifiex: fix sleep in atomic context bugs caused by dev_coredumpv

There are sleep in atomic context bugs when uploading device dump
data in mwifiex. The root cause is that dev_coredumpv could not
be used in atomic contexts, because it calls dev_set_name which
include operations that may sleep. The call tree shows execution
paths that could lead to bugs:

   (Interrupt context)
fw_dump_timer_fn
  mwifiex_upload_device_dump
    dev_coredumpv(..., GFP_KERNEL)
      dev_coredumpm()
        kzalloc(sizeof(*devcd), gfp); //may sleep
        dev_set_name
          kobject_set_name_vargs
            kvasprintf_const(GFP_KERNEL, ...); //may sleep
            kstrdup(s, GFP_KERNEL); //may sleep

In order to let dev_coredumpv support atomic contexts, this patch
changes the gfp_t parameter of kvasprintf_const and kstrdup in
kobject_set_name_vargs from GFP_KERNEL to GFP_ATOMIC. What's more,
In order to mitigate bug, this patch changes the gfp_t parameter
of dev_coredumpv from GFP_KERNEL to GFP_ATOMIC.

Fixes: 57670ee882d4 ("mwifiex: device dump support via devcoredump framework")
Signed-off-by: Duoming Zhou <duoming@....edu.cn>
---
Changes in v3:
  - Let dev_coredumpv support atomic contexts.

 drivers/net/wireless/marvell/mwifiex/main.c | 2 +-
 lib/kobject.c                               | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/main.c b/drivers/net/wireless/marvell/mwifiex/main.c
index ace7371c477..258906920a2 100644
--- a/drivers/net/wireless/marvell/mwifiex/main.c
+++ b/drivers/net/wireless/marvell/mwifiex/main.c
@@ -1116,7 +1116,7 @@ void mwifiex_upload_device_dump(struct mwifiex_adapter *adapter)
 	mwifiex_dbg(adapter, MSG,
 		    "== mwifiex dump information to /sys/class/devcoredump start\n");
 	dev_coredumpv(adapter->dev, adapter->devdump_data, adapter->devdump_len,
-		      GFP_KERNEL);
+		      GFP_ATOMIC);
 	mwifiex_dbg(adapter, MSG,
 		    "== mwifiex dump information to /sys/class/devcoredump end\n");
 
diff --git a/lib/kobject.c b/lib/kobject.c
index 5f0e71ab292..7672c54944c 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -254,7 +254,7 @@ int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
 	if (kobj->name && !fmt)
 		return 0;
 
-	s = kvasprintf_const(GFP_KERNEL, fmt, vargs);
+	s = kvasprintf_const(GFP_ATOMIC, fmt, vargs);
 	if (!s)
 		return -ENOMEM;
 
@@ -267,7 +267,7 @@ int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
 	if (strchr(s, '/')) {
 		char *t;
 
-		t = kstrdup(s, GFP_KERNEL);
+		t = kstrdup(s, GFP_ATOMIC);
 		kfree_const(s);
 		if (!t)
 			return -ENOMEM;
-- 
2.17.1