From: Dongliang Mu mudongliangabcd@gmail.com
[ Upstream commit 898f706695682b9954f280d95e49fa86ffa55d08 ]
Syzbot found a crash : UBSAN: shift-out-of-bounds in dbAllocAG. The underlying bug is the missing check of bmp->db_agl2size. The field can be greater than 64 and trigger the shift-out-of-bounds.
Fix this bug by adding a check of bmp->db_agl2size in dbMount since this field is used in many following functions. The upper bound for this field is L2MAXL2SIZE - L2MAXAG, thanks for the help of Dave Kleikamp. Note that, for maintenance, I reorganized error handling code of dbMount.
Reported-by: syzbot+15342c1aa6a00fb7a438@syzkaller.appspotmail.com Signed-off-by: Dongliang Mu mudongliangabcd@gmail.com Signed-off-by: Dave Kleikamp dave.kleikamp@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/jfs/jfs_dmap.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c index a07fbb60ac3c..a46fa0f3db57 100644 --- a/fs/jfs/jfs_dmap.c +++ b/fs/jfs/jfs_dmap.c @@ -168,7 +168,7 @@ int dbMount(struct inode *ipbmap) struct bmap *bmp; struct dbmap_disk *dbmp_le; struct metapage *mp; - int i; + int i, err;
/* * allocate/initialize the in-memory bmap descriptor @@ -183,8 +183,8 @@ int dbMount(struct inode *ipbmap) BMAPBLKNO << JFS_SBI(ipbmap->i_sb)->l2nbperpage, PSIZE, 0); if (mp == NULL) { - kfree(bmp); - return -EIO; + err = -EIO; + goto err_kfree_bmp; }
/* copy the on-disk bmap descriptor to its in-memory version. */ @@ -194,9 +194,8 @@ int dbMount(struct inode *ipbmap) bmp->db_l2nbperpage = le32_to_cpu(dbmp_le->dn_l2nbperpage); bmp->db_numag = le32_to_cpu(dbmp_le->dn_numag); if (!bmp->db_numag) { - release_metapage(mp); - kfree(bmp); - return -EINVAL; + err = -EINVAL; + goto err_release_metapage; }
bmp->db_maxlevel = le32_to_cpu(dbmp_le->dn_maxlevel); @@ -207,6 +206,11 @@ int dbMount(struct inode *ipbmap) bmp->db_agwidth = le32_to_cpu(dbmp_le->dn_agwidth); bmp->db_agstart = le32_to_cpu(dbmp_le->dn_agstart); bmp->db_agl2size = le32_to_cpu(dbmp_le->dn_agl2size); + if (bmp->db_agl2size > L2MAXL2SIZE - L2MAXAG) { + err = -EINVAL; + goto err_release_metapage; + } + for (i = 0; i < MAXAG; i++) bmp->db_agfree[i] = le64_to_cpu(dbmp_le->dn_agfree[i]); bmp->db_agsize = le64_to_cpu(dbmp_le->dn_agsize); @@ -227,6 +231,12 @@ int dbMount(struct inode *ipbmap) BMAP_LOCK_INIT(bmp);
return (0); + +err_release_metapage: + release_metapage(mp); +err_kfree_bmp: + kfree(bmp); + return err; }