Yes, this is a bug.
Steve, let's move
+ mid->callback(mid);
+
+ cifs_mid_q_entry_release(mid);
under ELSE {} block above.
We should probably move
+ dw->server->lstrp = jiffies;
before we looking for a mid.
--
Best regards,
Pavel Shilovsky
пт, 13 сент. 2019 г. в 06:47, Dan Carpenter <dan.carpenter@xxxxxxxxxx>:
>
> tree: git://git.samba.org/sfrench/cifs-2.6.git for-next
> head: 5fc321fb644fc787710353be11129edadd313f3a
> commit: a091c5f67c994d154e8faf95ab774644be2f4dd7 [24/31] smb3: allow parallelizing decryption of reads
>
> If you fix the issue, kindly add following tag
> Reported-by: kbuild test robot <lkp@xxxxxxxxx>
> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
>
> New smatch warnings:
> fs/cifs/smb2ops.c:4056 smb2_decrypt_offload() error: we previously assumed 'mid' could be null (see line 4045)
>
> git remote add cifs git://git.samba.org/sfrench/cifs-2.6.git
> git remote update cifs
> git checkout a091c5f67c994d154e8faf95ab774644be2f4dd7
> vim +/mid +4056 fs/cifs/smb2ops.c
>
> a091c5f67c994d Steve French 2019-09-07 4030 static void smb2_decrypt_offload(struct work_struct *work)
> a091c5f67c994d Steve French 2019-09-07 4031 {
> a091c5f67c994d Steve French 2019-09-07 4032 struct smb2_decrypt_work *dw = container_of(work,
> a091c5f67c994d Steve French 2019-09-07 4033 struct smb2_decrypt_work, decrypt);
> a091c5f67c994d Steve French 2019-09-07 4034 int i, rc;
> a091c5f67c994d Steve French 2019-09-07 4035 struct mid_q_entry *mid;
> a091c5f67c994d Steve French 2019-09-07 4036
> a091c5f67c994d Steve French 2019-09-07 4037 rc = decrypt_raw_data(dw->server, dw->buf, dw->server->vals->read_rsp_size,
> a091c5f67c994d Steve French 2019-09-07 4038 dw->ppages, dw->npages, dw->len);
> a091c5f67c994d Steve French 2019-09-07 4039 if (rc) {
> a091c5f67c994d Steve French 2019-09-07 4040 cifs_dbg(VFS, "error decrypting rc=%d\n", rc);
> a091c5f67c994d Steve French 2019-09-07 4041 goto free_pages;
> a091c5f67c994d Steve French 2019-09-07 4042 }
> a091c5f67c994d Steve French 2019-09-07 4043
> a091c5f67c994d Steve French 2019-09-07 4044 mid = smb2_find_mid(dw->server, dw->buf);
> a091c5f67c994d Steve French 2019-09-07 @4045 if (mid == NULL)
> a091c5f67c994d Steve French 2019-09-07 4046 cifs_dbg(FYI, "mid not found\n");
>
> Return here?
>
> a091c5f67c994d Steve French 2019-09-07 4047 else {
> a091c5f67c994d Steve French 2019-09-07 4048 mid->decrypted = true;
> a091c5f67c994d Steve French 2019-09-07 4049 rc = handle_read_data(dw->server, mid, dw->buf,
> a091c5f67c994d Steve French 2019-09-07 4050 dw->server->vals->read_rsp_size,
> a091c5f67c994d Steve French 2019-09-07 4051 dw->ppages, dw->npages, dw->len);
> a091c5f67c994d Steve French 2019-09-07 4052 }
> a091c5f67c994d Steve French 2019-09-07 4053
> a091c5f67c994d Steve French 2019-09-07 4054 dw->server->lstrp = jiffies;
> a091c5f67c994d Steve French 2019-09-07 4055
> a091c5f67c994d Steve French 2019-09-07 @4056 mid->callback(mid);
> ^^^^^^^^^^^^^
> Potential NULL derference.
>
> a091c5f67c994d Steve French 2019-09-07 4057
> a091c5f67c994d Steve French 2019-09-07 4058 cifs_mid_q_entry_release(mid);
> a091c5f67c994d Steve French 2019-09-07 4059
> a091c5f67c994d Steve French 2019-09-07 4060 free_pages:
> a091c5f67c994d Steve French 2019-09-07 4061 for (i = dw->npages-1; i >= 0; i--)
> a091c5f67c994d Steve French 2019-09-07 4062 put_page(dw->ppages[i]);
> a091c5f67c994d Steve French 2019-09-07 4063
> a091c5f67c994d Steve French 2019-09-07 4064 kfree(dw->ppages);
> a091c5f67c994d Steve French 2019-09-07 4065 cifs_small_buf_release(dw->buf);
> a091c5f67c994d Steve French 2019-09-07 4066 }
>
> ---
> 0-DAY kernel test infrastructure Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all Intel Corporation
