linux-kernel - [syzbot] [jfs?] KASAN: slab-use-after-free Read in dbFreeBits

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Message-ID: <tencent_6A26ED06CF0C782A6ECC2CC56E209458EA0A@qq.com>
Date: Sat, 24 Aug 2024 09:37:12 +0800
From: Edward Adam Davis <eadavis@...com>
To: syzbot+3c010e21296f33a5dc16@...kaller.appspotmail.com
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [jfs?] KASAN: slab-use-after-free Read in dbFreeBits

sync jfs remount and  jfs ioctrl with s_umount

#syz test: upstream master

diff --git a/fs/jfs/jfs_discard.c b/fs/jfs/jfs_discard.c
index 575cb2ba74fc..5f4b305030ad 100644
--- a/fs/jfs/jfs_discard.c
+++ b/fs/jfs/jfs_discard.c
@@ -65,7 +65,7 @@ void jfs_issue_discard(struct inode *ip, u64 blkno, u64 nblocks)
 int jfs_ioc_trim(struct inode *ip, struct fstrim_range *range)
 {
 	struct inode *ipbmap = JFS_SBI(ip->i_sb)->ipbmap;
-	struct bmap *bmp = JFS_SBI(ip->i_sb)->bmap;
+	struct bmap *bmp;
 	struct super_block *sb = ipbmap->i_sb;
 	int agno, agno_end;
 	u64 start, end, minlen;
@@ -83,10 +83,15 @@ int jfs_ioc_trim(struct inode *ip, struct fstrim_range *range)
 	if (minlen == 0)
 		minlen = 1;
 
+	down_read(&sb->s_umount);
+	bmp = JFS_SBI(ip->i_sb)->bmap;
+
 	if (minlen > bmp->db_agsize ||
 	    start >= bmp->db_mapsize ||
-	    range->len < sb->s_blocksize)
+	    range->len < sb->s_blocksize) {
+		up_read(&sb->s_umount);
 		return -EINVAL;
+	}
 
 	if (end >= bmp->db_mapsize)
 		end = bmp->db_mapsize - 1;
@@ -100,6 +105,8 @@ int jfs_ioc_trim(struct inode *ip, struct fstrim_range *range)
 		trimmed += dbDiscardAG(ip, agno, minlen);
 		agno++;
 	}
+
+	up_read(&sb->s_umount);
 	range->len = trimmed << sb->s_blocksize_bits;
 
 	return 0;