[ammarfaizi2-block:dhowells/linux-fs/cifs-for-viro 5/8] fs/cifs/smb2ops.c:4994:7: warning: variable 'length' is used uninitialized whenever 'if' condition is false

From: kernel test robot
Date: Thu Jul 07 2022 - 21:35:27 EST

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tree: https://github.com/ammarfaizi2/linux-block dhowells/linux-fs/cifs-for-viro
head: 569e0acf4192ada33675e44b24701e679d87ebc9
commit: f398cb911105297654980b5973ff230323061fce [5/8] cifs: Change the I/O paths to use an iterator rather than a page list
config: x86_64-randconfig-a012 (https://download.01.org/0day-ci/archive/20220708/202207080923.s0L0sZLm-lkp@xxxxxxxxx/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 562c3467a6738aa89203f72fc1d1343e5baadf3c)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/ammarfaizi2/linux-block/commit/f398cb911105297654980b5973ff230323061fce
git remote add ammarfaizi2-block https://github.com/ammarfaizi2/linux-block
git fetch --no-tags ammarfaizi2-block dhowells/linux-fs/cifs-for-viro
git checkout f398cb911105297654980b5973ff230323061fce
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash fs/cifs/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

>> fs/cifs/smb2ops.c:4994:7: warning: variable 'length' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
if (rdata->result != 0) {
^~~~~~~~~~~~~~~~~~
fs/cifs/smb2ops.c:5026:9: note: uninitialized use occurs here
return length;
^~~~~~
fs/cifs/smb2ops.c:4994:3: note: remove the 'if' if its condition is always true
if (rdata->result != 0) {
^~~~~~~~~~~~~~~~~~~~~~~~
fs/cifs/smb2ops.c:4893:12: note: initialize the variable 'length' to silence this warning
int length;
^
= 0
1 warning generated.

vim +4994 fs/cifs/smb2ops.c

c42a6abe301283 Pavel Shilovsky 2016-11-17 4880
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4881 static int
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4882 handle_read_data(struct TCP_Server_Info *server, struct mid_q_entry *mid,
f398cb91110529 David Howells 2022-01-24 4883 char *buf, unsigned int buf_len, struct xarray *pages,
f398cb91110529 David Howells 2022-01-24 4884 unsigned int pages_len, bool is_offloaded)
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4885 {
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4886 unsigned int data_offset;
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4887 unsigned int data_len;
c42a6abe301283 Pavel Shilovsky 2016-11-17 4888 unsigned int cur_off;
c42a6abe301283 Pavel Shilovsky 2016-11-17 4889 unsigned int cur_page_idx;
c42a6abe301283 Pavel Shilovsky 2016-11-17 4890 unsigned int pad_len;
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4891 struct cifs_readdata *rdata = mid->callback_data;
0d35e382e4e96a Ronnie Sahlberg 2021-11-05 4892 struct smb2_hdr *shdr = (struct smb2_hdr *)buf;
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4893 int length;
74dcf418fe3446 Long Li 2017-11-22 4894 bool use_rdma_mr = false;
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4895
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4896 if (shdr->Command != SMB2_READ) {
3175eb9b577e82 Ronnie Sahlberg 2019-09-04 4897 cifs_server_dbg(VFS, "only big read responses are supported\n");
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4898 return -ENOTSUPP;
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4899 }
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4900
511c54a2f69195 Pavel Shilovsky 2017-07-08 4901 if (server->ops->is_session_expired &&
511c54a2f69195 Pavel Shilovsky 2017-07-08 4902 server->ops->is_session_expired(buf)) {
de9ac0a6e9efdf Rohith Surabattula 2020-10-28 4903 if (!is_offloaded)
183eea2ee5ba96 Shyam Prasad N 2021-07-19 4904 cifs_reconnect(server, true);
511c54a2f69195 Pavel Shilovsky 2017-07-08 4905 return -1;
511c54a2f69195 Pavel Shilovsky 2017-07-08 4906 }
511c54a2f69195 Pavel Shilovsky 2017-07-08 4907
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4908 if (server->ops->is_status_pending &&
66265f134acfb2 Pavel Shilovsky 2019-01-23 4909 server->ops->is_status_pending(buf, server))
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4910 return -1;
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4911
ec678eae746dd2 Pavel Shilovsky 2019-01-18 4912 /* set up first two iov to get credits */
ec678eae746dd2 Pavel Shilovsky 2019-01-18 4913 rdata->iov[0].iov_base = buf;
bb1bccb60c2ebd Pavel Shilovsky 2019-01-17 4914 rdata->iov[0].iov_len = 0;
bb1bccb60c2ebd Pavel Shilovsky 2019-01-17 4915 rdata->iov[1].iov_base = buf;
ec678eae746dd2 Pavel Shilovsky 2019-01-18 4916 rdata->iov[1].iov_len =
bb1bccb60c2ebd Pavel Shilovsky 2019-01-17 4917 min_t(unsigned int, buf_len, server->vals->read_rsp_size);
ec678eae746dd2 Pavel Shilovsky 2019-01-18 4918 cifs_dbg(FYI, "0: iov_base=%p iov_len=%zu\n",
ec678eae746dd2 Pavel Shilovsky 2019-01-18 4919 rdata->iov[0].iov_base, rdata->iov[0].iov_len);
ec678eae746dd2 Pavel Shilovsky 2019-01-18 4920 cifs_dbg(FYI, "1: iov_base=%p iov_len=%zu\n",
ec678eae746dd2 Pavel Shilovsky 2019-01-18 4921 rdata->iov[1].iov_base, rdata->iov[1].iov_len);
ec678eae746dd2 Pavel Shilovsky 2019-01-18 4922
ec678eae746dd2 Pavel Shilovsky 2019-01-18 4923 rdata->result = server->ops->map_error(buf, true);
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4924 if (rdata->result != 0) {
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4925 cifs_dbg(FYI, "%s: server returned error %d\n",
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4926 __func__, rdata->result);
ec678eae746dd2 Pavel Shilovsky 2019-01-18 4927 /* normal error on read response */
ac873aa3dc2170 Rohith Surabattula 2020-10-29 4928 if (is_offloaded)
ac873aa3dc2170 Rohith Surabattula 2020-10-29 4929 mid->mid_state = MID_RESPONSE_RECEIVED;
ac873aa3dc2170 Rohith Surabattula 2020-10-29 4930 else
ec678eae746dd2 Pavel Shilovsky 2019-01-18 4931 dequeue_mid(mid, false);
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4932 return 0;
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4933 }
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4934
1fc6ad2f10ad6f Ronnie Sahlberg 2018-06-01 4935 data_offset = server->ops->read_data_offset(buf);
74dcf418fe3446 Long Li 2017-11-22 4936 #ifdef CONFIG_CIFS_SMB_DIRECT
74dcf418fe3446 Long Li 2017-11-22 4937 use_rdma_mr = rdata->mr;
74dcf418fe3446 Long Li 2017-11-22 4938 #endif
74dcf418fe3446 Long Li 2017-11-22 4939 data_len = server->ops->read_data_length(buf, use_rdma_mr);
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4940
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4941 if (data_offset < server->vals->read_rsp_size) {
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4942 /*
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4943 * win2k8 sometimes sends an offset of 0 when the read
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4944 * is beyond the EOF. Treat it as if the data starts just after
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4945 * the header.
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4946 */
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4947 cifs_dbg(FYI, "%s: data offset (%u) inside read response header\n",
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4948 __func__, data_offset);
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4949 data_offset = server->vals->read_rsp_size;
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4950 } else if (data_offset > MAX_CIFS_SMALL_BUFFER_SIZE) {
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4951 /* data_offset is beyond the end of smallbuf */
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4952 cifs_dbg(FYI, "%s: data offset (%u) beyond end of smallbuf\n",
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4953 __func__, data_offset);
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4954 rdata->result = -EIO;
ac873aa3dc2170 Rohith Surabattula 2020-10-29 4955 if (is_offloaded)
ac873aa3dc2170 Rohith Surabattula 2020-10-29 4956 mid->mid_state = MID_RESPONSE_MALFORMED;
ac873aa3dc2170 Rohith Surabattula 2020-10-29 4957 else
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4958 dequeue_mid(mid, rdata->result);
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4959 return 0;
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4960 }
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4961
c42a6abe301283 Pavel Shilovsky 2016-11-17 4962 pad_len = data_offset - server->vals->read_rsp_size;
c42a6abe301283 Pavel Shilovsky 2016-11-17 4963
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4964 if (buf_len <= data_offset) {
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 4965 /* read response payload is in pages */
c42a6abe301283 Pavel Shilovsky 2016-11-17 4966 cur_page_idx = pad_len / PAGE_SIZE;
c42a6abe301283 Pavel Shilovsky 2016-11-17 4967 cur_off = pad_len % PAGE_SIZE;
c42a6abe301283 Pavel Shilovsky 2016-11-17 4968
c42a6abe301283 Pavel Shilovsky 2016-11-17 4969 if (cur_page_idx != 0) {
c42a6abe301283 Pavel Shilovsky 2016-11-17 4970 /* data offset is beyond the 1st page of response */
c42a6abe301283 Pavel Shilovsky 2016-11-17 4971 cifs_dbg(FYI, "%s: data offset (%u) beyond 1st page of response\n",
c42a6abe301283 Pavel Shilovsky 2016-11-17 4972 __func__, data_offset);
c42a6abe301283 Pavel Shilovsky 2016-11-17 4973 rdata->result = -EIO;
ac873aa3dc2170 Rohith Surabattula 2020-10-29 4974 if (is_offloaded)
ac873aa3dc2170 Rohith Surabattula 2020-10-29 4975 mid->mid_state = MID_RESPONSE_MALFORMED;
ac873aa3dc2170 Rohith Surabattula 2020-10-29 4976 else
c42a6abe301283 Pavel Shilovsky 2016-11-17 4977 dequeue_mid(mid, rdata->result);
c42a6abe301283 Pavel Shilovsky 2016-11-17 4978 return 0;
c42a6abe301283 Pavel Shilovsky 2016-11-17 4979 }
c42a6abe301283 Pavel Shilovsky 2016-11-17 4980
f398cb91110529 David Howells 2022-01-24 4981 if (data_len > pages_len - pad_len) {
c42a6abe301283 Pavel Shilovsky 2016-11-17 4982 /* data_len is corrupt -- discard frame */
c42a6abe301283 Pavel Shilovsky 2016-11-17 4983 rdata->result = -EIO;
ac873aa3dc2170 Rohith Surabattula 2020-10-29 4984 if (is_offloaded)
ac873aa3dc2170 Rohith Surabattula 2020-10-29 4985 mid->mid_state = MID_RESPONSE_MALFORMED;
ac873aa3dc2170 Rohith Surabattula 2020-10-29 4986 else
c42a6abe301283 Pavel Shilovsky 2016-11-17 4987 dequeue_mid(mid, rdata->result);
c42a6abe301283 Pavel Shilovsky 2016-11-17 4988 return 0;
c42a6abe301283 Pavel Shilovsky 2016-11-17 4989 }
c42a6abe301283 Pavel Shilovsky 2016-11-17 4990
f398cb91110529 David Howells 2022-01-24 4991 /* Copy the data to the output I/O iterator. */
f398cb91110529 David Howells 2022-01-24 4992 rdata->result = cifs_copy_pages_to_iter(pages, pages_len,
f398cb91110529 David Howells 2022-01-24 4993 cur_off, &rdata->iter);
c42a6abe301283 Pavel Shilovsky 2016-11-17 @4994 if (rdata->result != 0) {
ac873aa3dc2170 Rohith Surabattula 2020-10-29 4995 if (is_offloaded)
ac873aa3dc2170 Rohith Surabattula 2020-10-29 4996 mid->mid_state = MID_RESPONSE_MALFORMED;
ac873aa3dc2170 Rohith Surabattula 2020-10-29 4997 else
c42a6abe301283 Pavel Shilovsky 2016-11-17 4998 dequeue_mid(mid, rdata->result);
c42a6abe301283 Pavel Shilovsky 2016-11-17 4999 return 0;
c42a6abe301283 Pavel Shilovsky 2016-11-17 5000 }
f398cb91110529 David Howells 2022-01-24 5001 rdata->got_bytes = pages_len;
c42a6abe301283 Pavel Shilovsky 2016-11-17 5002
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 5003 } else if (buf_len >= data_offset + data_len) {
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 5004 /* read response payload is in buf */
f398cb91110529 David Howells 2022-01-24 5005 WARN_ONCE(pages && !xa_empty(pages),
f398cb91110529 David Howells 2022-01-24 5006 "read data can be either in buf or in pages");
f398cb91110529 David Howells 2022-01-24 5007 length = copy_to_iter(buf + data_offset, data_len, &rdata->iter);
f398cb91110529 David Howells 2022-01-24 5008 if (length < 0)
f398cb91110529 David Howells 2022-01-24 5009 return length;
f398cb91110529 David Howells 2022-01-24 5010 rdata->got_bytes = data_len;
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 5011 } else {
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 5012 /* read response payload cannot be in both buf and pages */
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 5013 WARN_ONCE(1, "buf can not contain only a part of read data");
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 5014 rdata->result = -EIO;
ac873aa3dc2170 Rohith Surabattula 2020-10-29 5015 if (is_offloaded)
ac873aa3dc2170 Rohith Surabattula 2020-10-29 5016 mid->mid_state = MID_RESPONSE_MALFORMED;
ac873aa3dc2170 Rohith Surabattula 2020-10-29 5017 else
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 5018 dequeue_mid(mid, rdata->result);
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 5019 return 0;
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 5020 }
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 5021
ac873aa3dc2170 Rohith Surabattula 2020-10-29 5022 if (is_offloaded)
ac873aa3dc2170 Rohith Surabattula 2020-10-29 5023 mid->mid_state = MID_RESPONSE_RECEIVED;
ac873aa3dc2170 Rohith Surabattula 2020-10-29 5024 else
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 5025 dequeue_mid(mid, false);
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 5026 return length;
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 5027 }
4326ed2f6a16ae Pavel Shilovsky 2016-11-17 5028

:::::: The code at line 4994 was first introduced by commit
:::::: c42a6abe3012832a68a371dabe17c2ced97e62ad CIFS: Add capability to decrypt big read responses

:::::: TO: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
:::::: CC: Steve French <smfrench@xxxxxxxxx>

--
0-DAY CI Kernel Test Service
https://01.org/lkp

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