linux-kernel - [PATCH] ubifs: Fix a sleep-in-atomic bug in ubifs_read

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Message-Id: <1496633916-32362-1-git-send-email-baijiaju1990@163.com>
Date:   Mon,  5 Jun 2017 11:38:36 +0800
From:   Jia-Ju Bai <baijiaju1990@....com>
To:     richard@....at, dedekind1@...il.com
Cc:     linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@....com>
Subject: [PATCH] ubifs: Fix a sleep-in-atomic bug in ubifs_read_nnode

The driver may sleep under a spin lock, and the function call path is:
ubifs_change_lp (acquire the lock by spin_lock)
  change_category
    ubifs_remove_from_cat
      remove_from_lpt_heap
        dbg_check_heap
          ubifs_lpt_lookup
            ubifs_read_nnode
              kzalloc(GFP_NOFS) --> may sleep

To fix it, "GFP_NOFS" is replaced with "GFP_ATOMIC".

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

diff --git a/fs/ubifs/lpt.c b/fs/ubifs/lpt.c
index 9a51710..4247934c 100644
--- a/fs/ubifs/lpt.c
+++ b/fs/ubifs/lpt.c
@@ -1205,7 +1205,7 @@ int ubifs_read_nnode(struct ubifs_info *c, struct ubifs_nnode *parent, int iip)
 		lnum = c->lpt_lnum;
 		offs = c->lpt_offs;
 	}
-	nnode = kzalloc(sizeof(struct ubifs_nnode), GFP_NOFS);
+	nnode = kzalloc(sizeof(struct ubifs_nnode), GFP_ATOMIC);
 	if (!nnode) {
 		err = -ENOMEM;
 		goto out;
-- 
1.7.9.5