Re: [samba-ksmbd:ksmbd-for-next-next 12/12] fs/ksmbd/smbacl.c:1213 smb_check_perm_dacl() warn: variable dereferenced before check 'pntsd' (see line 1212)

[Namjae Jeon]

2022-08-01 21:10 GMT+09:00, Dan Carpenter <dan.carpenter@xxxxxxxxxx>:
> tree:   git://git.samba.org/ksmbd.git ksmbd-for-next-next
> head:   d0b73d20ca9100c7b969b65d8a1ff49cdd1fa9c9
> commit: d0b73d20ca9100c7b969b65d8a1ff49cdd1fa9c9 [12/12] ksmbd: fix
> heap-based overflow in set_ntacl_dacl()
> config: arc-randconfig-m041-20220731
> (https://download.01.org/0day-ci/archive/20220801/202208010716.Io52CJih-lkp@xxxxxxxxx/config)
> compiler: arceb-elf-gcc (GCC) 12.1.0
>
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Hi Dan,

I will fix it.

Thanks for your report!
>
> New smatch warnings:
> fs/ksmbd/smbacl.c:1213 smb_check_perm_dacl() warn: variable dereferenced
> before check 'pntsd' (see line 1212)
> fs/ksmbd/smb2pdu.c:5182 smb2_get_info_sec() error: uninitialized symbol
> 'secdesclen'.
>
> Old smatch warnings:
> fs/ksmbd/smb2pdu.c:549 smb2_allocate_rsp_buf() warn: Please consider using
> kvzalloc instead of kvmalloc
> fs/ksmbd/smb2pdu.c:6123 smb2_read_pipe() warn: Please consider using
> kvzalloc instead of kvmalloc
> fs/ksmbd/smb2pdu.c:6275 smb2_read() warn: Please consider using kvzalloc
> instead of kvmalloc
> fs/ksmbd/smb2pdu.c:6424 smb2_write_rdma_channel() warn: Please consider
> using kvzalloc instead of kvmalloc
>
> vim +/pntsd +1213 fs/ksmbd/smbacl.c
>
> ef24c962d0f290 fs/ksmbd/smbacl.c Hyunchul Lee      2021-06-30  1188  int
> smb_check_perm_dacl(struct ksmbd_conn *conn, struct path *path,
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1189
> 			__le32 *pdaccess, int uid)
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1190  {
> 465d720485eff1 fs/ksmbd/smbacl.c Hyunchul Lee      2021-07-03  1191  	struct
> user_namespace *user_ns = mnt_user_ns(path->mnt);
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1192  	struct
> smb_ntsd *pntsd = NULL;
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1193  	struct
> smb_acl *pdacl;
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1194  	struct
> posix_acl *posix_acls;
> d0b73d20ca9100 fs/ksmbd/smbacl.c Namjae Jeon       2022-07-28  1195  	int rc
> = 0, pntsd_size, acl_size, aces_size, pdacl_size, dacl_offset;
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1196  	struct
> smb_sid sid;
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1197  	int
> granted = le32_to_cpu(*pdaccess & ~FILE_MAXIMAL_ACCESS_LE);
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1198  	struct
> smb_ace *ace;
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1199  	int i,
> found = 0;
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1200
> 	unsigned int access_bits = 0;
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1201  	struct
> smb_ace *others_ace = NULL;
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1202  	struct
> posix_acl_entry *pa_entry;
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1203
> 	unsigned int sid_type = SIDOWNER;
> d0b73d20ca9100 fs/ksmbd/smbacl.c Namjae Jeon       2022-07-28  1204
> 	unsigned short ace_size;
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1205
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1206
> 	ksmbd_debug(SMB, "check permission using windows acl\n");
> d0b73d20ca9100 fs/ksmbd/smbacl.c Namjae Jeon       2022-07-28  1207
> 	pntsd_size = ksmbd_vfs_get_sd_xattr(conn, user_ns,
> af34983e831587 fs/ksmbd/smbacl.c Hyunchul Lee      2021-06-30  1208  					
>  path->dentry, &pntsd);
> d0b73d20ca9100 fs/ksmbd/smbacl.c Namjae Jeon       2022-07-28  1209  	if
> (pntsd_size <= 0)
> d0b73d20ca9100 fs/ksmbd/smbacl.c Namjae Jeon       2022-07-28  1210  		goto
> err_out;
> d0b73d20ca9100 fs/ksmbd/smbacl.c Namjae Jeon       2022-07-28  1211
> d0b73d20ca9100 fs/ksmbd/smbacl.c Namjae Jeon       2022-07-28 @1212
> 	dacl_offset = le32_to_cpu(pntsd->dacloffset);
>
>                      ^^^^^^^^^^^^^^^^^
> Dereference
>
> d0b73d20ca9100 fs/ksmbd/smbacl.c Namjae Jeon       2022-07-28 @1213  	if
> (!pntsd || !pntsd->dacloffset ||
>
> ^^^^^
> Checked too late
>
> d0b73d20ca9100 fs/ksmbd/smbacl.c Namjae Jeon       2022-07-28  1214  	
> (dacl_offset + sizeof(struct smb_acl) > pntsd_size))
> d0b73d20ca9100 fs/ksmbd/smbacl.c Namjae Jeon       2022-07-28  1215  		goto
> err_out;
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1216
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1217  	pdacl
> = (struct smb_acl *)((char *)pntsd + le32_to_cpu(pntsd->dacloffset));
> d0b73d20ca9100 fs/ksmbd/smbacl.c Namjae Jeon       2022-07-28  1218
> 	acl_size = pntsd_size - dacl_offset;
> d0b73d20ca9100 fs/ksmbd/smbacl.c Namjae Jeon       2022-07-28  1219
> 	pdacl_size = le16_to_cpu(pdacl->size);
> 50355b0b20103a fs/cifsd/smbacl.c Namjae Jeon       2021-03-19  1220
> d0b73d20ca9100 fs/ksmbd/smbacl.c Namjae Jeon       2022-07-28  1221  	if
> (pdacl_size > acl_size || pdacl_size < sizeof(struct smb_acl))
> d0b73d20ca9100 fs/ksmbd/smbacl.c Namjae Jeon       2022-07-28  1222  		goto
> err_out;
> 50355b0b20103a fs/cifsd/smbacl.c Namjae Jeon       2021-03-19  1223
> e2f34481b24db2 fs/cifsd/smbacl.c Namjae Jeon       2021-03-16  1224  	if
> (!pdacl->num_aces) {
>
> --
> 0-DAY CI Kernel Test Service
> https://01.org/lkp
>
>