From: Jan Kara <jack@suse.cz>
Date: Mon, 9 Oct 2017 14:46:40 +0000 (+0200)
Subject: ext2: Fix possible sleep in atomic during mount option parsing
X-Git-Tag: v4.15-rc1~130^2^2~9
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=8af634ff9e5c0fd5daff37c9759cd6594345b372;p=linux.git

ext2: Fix possible sleep in atomic during mount option parsing

match_int() used in mount option parsing can allocate memory using
GFP_KERNEL and thus sleep. Avoid parsing mount options with sbi->s_lock
held.

Signed-off-by: Jan Kara <jack@suse.cz>
---

diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 05eae20d133f..e2b6be03e69b 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -1321,20 +1321,20 @@ static int ext2_remount (struct super_block * sb, int * flags, char * data)
 	int err;
 
 	sync_filesystem(sb);
-	spin_lock(&sbi->s_lock);
 
+	spin_lock(&sbi->s_lock);
 	new_opts.s_mount_opt = sbi->s_mount_opt;
 	new_opts.s_resuid = sbi->s_resuid;
 	new_opts.s_resgid = sbi->s_resgid;
+	spin_unlock(&sbi->s_lock);
 
 	/*
 	 * Allow the "check" option to be passed as a remount option.
 	 */
-	if (!parse_options(data, sb, &new_opts)) {
-		spin_unlock(&sbi->s_lock);
+	if (!parse_options(data, sb, &new_opts))
 		return -EINVAL;
-	}
 
+	spin_lock(&sbi->s_lock);
 	es = sbi->s_es;
 	if ((sbi->s_mount_opt ^ new_opts.s_mount_opt) & EXT2_MOUNT_DAX) {
 		ext2_msg(sb, KERN_WARNING, "warning: refusing change of "