tmpfs,ceph,gfs2,isofs,reiserfs,xfs: fix fh_len checking

Fuzzing with trinity oopsed on the 1st instruction of shmem_fh_to_dentry(),
	u64 inum = fid->raw[2];
which is unhelpfully reported as at the end of shmem_alloc_inode():

BUG: unable to handle kernel paging request at ffff880061cd3000
IP: [<ffffffff812190d0>] shmem_alloc_inode+0x40/0x40
Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
Call Trace:
 [<ffffffff81488649>] ? exportfs_decode_fh+0x79/0x2d0
 [<ffffffff812d77c3>] do_handle_open+0x163/0x2c0
 [<ffffffff812d792c>] sys_open_by_handle_at+0xc/0x10
 [<ffffffff83a5f3f8>] tracesys+0xe1/0xe6

Right, tmpfs is being stupid to access fid->raw[2] before validating that
fh_len includes it: the buffer kmalloc'ed by do_sys_name_to_handle() may
fall at the end of a page, and the next page not be present.

But some other filesystems (ceph, gfs2, isofs, reiserfs, xfs) are being
careless about fh_len too, in fh_to_dentry() and/or fh_to_parent(), and
could oops in the same way: add the missing fh_len checks to those.

Reported-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Sage Weil <sage@inktank.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/ceph/export.c b/fs/ceph/export.c
index 8e1b60e..02ce909 100644 (file)
--- a/fs/ceph/export.c
+++ b/fs/ceph/export.c
@@ -99,7 +99,7 @@ static int ceph_encode_fh(struct inode *inode, u32 *rawfh, int *max_len,
  * FIXME: we should try harder by querying the mds for the ino.
  */
 static struct dentry *__fh_to_dentry(struct super_block *sb,
-                                    struct ceph_nfs_fh *fh)
+                                    struct ceph_nfs_fh *fh, int fh_len)
 {
        struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc;
        struct inode *inode;
@@ -107,6 +107,9 @@ static struct dentry *__fh_to_dentry(struct super_block *sb,
        struct ceph_vino vino;
        int err;
 
+       if (fh_len < sizeof(*fh) / 4)
+               return ERR_PTR(-ESTALE);
+
        dout("__fh_to_dentry %llx\n", fh->ino);
        vino.ino = fh->ino;
        vino.snap = CEPH_NOSNAP;
@@ -150,7 +153,7 @@ static struct dentry *__fh_to_dentry(struct super_block *sb,
  * convert connectable fh to dentry
  */
 static struct dentry *__cfh_to_dentry(struct super_block *sb,
-                                     struct ceph_nfs_confh *cfh)
+                                     struct ceph_nfs_confh *cfh, int fh_len)
 {
        struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc;
        struct inode *inode;
@@ -158,6 +161,9 @@ static struct dentry *__cfh_to_dentry(struct super_block *sb,
        struct ceph_vino vino;
        int err;
 
+       if (fh_len < sizeof(*cfh) / 4)
+               return ERR_PTR(-ESTALE);
+
        dout("__cfh_to_dentry %llx (%llx/%x)\n",
             cfh->ino, cfh->parent_ino, cfh->parent_name_hash);
 
@@ -207,9 +213,11 @@ static struct dentry *ceph_fh_to_dentry(struct super_block *sb, struct fid *fid,
                                        int fh_len, int fh_type)
 {
        if (fh_type == 1)
-               return __fh_to_dentry(sb, (struct ceph_nfs_fh *)fid->raw);
+               return __fh_to_dentry(sb, (struct ceph_nfs_fh *)fid->raw,
+                                                               fh_len);
        else
-               return __cfh_to_dentry(sb, (struct ceph_nfs_confh *)fid->raw);
+               return __cfh_to_dentry(sb, (struct ceph_nfs_confh *)fid->raw,
+                                                               fh_len);
 }
 
 /*
@@ -230,6 +238,8 @@ static struct dentry *ceph_fh_to_parent(struct super_block *sb,
 
        if (fh_type == 1)
                return ERR_PTR(-ESTALE);
+       if (fh_len < sizeof(*cfh) / 4)
+               return ERR_PTR(-ESTALE);
 
        pr_debug("fh_to_parent %llx/%d\n", cfh->parent_ino,
                 cfh->parent_name_hash);

diff --git a/fs/gfs2/export.c b/fs/gfs2/export.c
index e8ed6d4..4767774 100644 (file)
--- a/fs/gfs2/export.c
+++ b/fs/gfs2/export.c
@@ -161,6 +161,8 @@ static struct dentry *gfs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
        case GFS2_SMALL_FH_SIZE:
        case GFS2_LARGE_FH_SIZE:
        case GFS2_OLD_FH_SIZE:
+               if (fh_len < GFS2_SMALL_FH_SIZE)
+                       return NULL;
                this.no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
                this.no_formal_ino |= be32_to_cpu(fh[1]);
                this.no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
@@ -180,6 +182,8 @@ static struct dentry *gfs2_fh_to_parent(struct super_block *sb, struct fid *fid,
        switch (fh_type) {
        case GFS2_LARGE_FH_SIZE:
        case GFS2_OLD_FH_SIZE:
+               if (fh_len < GFS2_LARGE_FH_SIZE)
+                       return NULL;
                parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
                parent.no_formal_ino |= be32_to_cpu(fh[5]);
                parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;

diff --git a/fs/isofs/export.c b/fs/isofs/export.c
index 1d38044..2b4f235 100644 (file)
--- a/fs/isofs/export.c
+++ b/fs/isofs/export.c
@@ -175,7 +175,7 @@ static struct dentry *isofs_fh_to_parent(struct super_block *sb,
 {
        struct isofs_fid *ifid = (struct isofs_fid *)fid;
 
-       if (fh_type != 2)
+       if (fh_len < 2 || fh_type != 2)
                return NULL;
 
        return isofs_export_iget(sb,

diff --git a/fs/reiserfs/inode.c b/fs/reiserfs/inode.c
index 4648555..f27f01a 100644 (file)
--- a/fs/reiserfs/inode.c
+++ b/fs/reiserfs/inode.c
@@ -1573,8 +1573,10 @@ struct dentry *reiserfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
                        reiserfs_warning(sb, "reiserfs-13077",
                                "nfsd/reiserfs, fhtype=%d, len=%d - odd",
                                fh_type, fh_len);
-               fh_type = 5;
+               fh_type = fh_len;
        }
+       if (fh_len < 2)
+               return NULL;
 
        return reiserfs_get_dentry(sb, fid->raw[0], fid->raw[1],
                (fh_type == 3 || fh_type >= 5) ? fid->raw[2] : 0);
@@ -1583,6 +1585,8 @@ struct dentry *reiserfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 struct dentry *reiserfs_fh_to_parent(struct super_block *sb, struct fid *fid,
                int fh_len, int fh_type)
 {
+       if (fh_type > fh_len)
+               fh_type = fh_len;
        if (fh_type < 4)
                return NULL;
 

diff --git a/fs/xfs/xfs_export.c b/fs/xfs/xfs_export.c
index 4267922..8c6d1d7 100644 (file)
--- a/fs/xfs/xfs_export.c
+++ b/fs/xfs/xfs_export.c
@@ -189,6 +189,9 @@ xfs_fs_fh_to_parent(struct super_block *sb, struct fid *fid,
        struct xfs_fid64        *fid64 = (struct xfs_fid64 *)fid;
        struct inode            *inode = NULL;
 
+       if (fh_len < xfs_fileid_length(fileid_type))
+               return NULL;
+
        switch (fileid_type) {
        case FILEID_INO32_GEN_PARENT:
                inode = xfs_nfs_get_inode(sb, fid->i32.parent_ino,

diff --git a/mm/shmem.c b/mm/shmem.c
index cc12072..67afba5 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2220,12 +2220,14 @@ static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
 {
        struct inode *inode;
        struct dentry *dentry = NULL;
-       u64 inum = fid->raw[2];
-       inum = (inum << 32) | fid->raw[1];
+       u64 inum;
 
        if (fh_len < 3)
                return NULL;
 
+       inum = fid->raw[2];
+       inum = (inum << 32) | fid->raw[1];
+
        inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
                        shmem_match, fid->raw);
        if (inode) {