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

From: Edward Adam Davis
Date: Fri Aug 23 2024 - 21:37:39 EST


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;