linux-ext4 - [PATCH] ext2/super: Fix a possible sleep-in-atomic bug in parse

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Date:   Sat,  7 Oct 2017 09:20:46 +0800
From:   Jia-Ju Bai <baijiaju1990@....com>
To:     viro@...iv.linux.org.uk, jack@...e.com, sagi@...mberg.me,
        james.smart@...adcom.com
Cc:     linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, Jia-Ju Bai <baijiaju1990@....com>
Subject: [PATCH] ext2/super: Fix a possible sleep-in-atomic bug in parse_options

The kernel may sleep under a spinlock, and the function call path is:
ext2_remount
  parse_options
    match_int
      match_number (lib/parser.c)
        kmalloc(GFP_KERNEL) --> may sleep

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

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

diff --git a/lib/parser.c b/lib/parser.c
index 3278958..bc6e2ce 100644
--- a/lib/parser.c
+++ b/lib/parser.c
@@ -133,7 +133,7 @@ static int match_number(substring_t *s, int *result, int base)
 	long val;
 	size_t len = s->to - s->from;
 
-	buf = kmalloc(len + 1, GFP_KERNEL);
+	buf = kmalloc(len + 1, GFP_ATOMIC);
 	if (!buf)
 		return -ENOMEM;
 	memcpy(buf, s->from, len);
-- 
1.7.9.5