linux.git/net/9p/client.c, branch v6.8

9p/net: fix possible memory leak in p9_check_errors()

2023-10-27T03:44:13+00:00

When p9pdu_readf() is called with "s?d" attribute, it allocates a pointer
that will store a string. But when p9pdu_readf() fails while handling "d"
then this pointer will not be freed in p9_check_errors().

Fixes: 51a87c552dfd ("9p: rework client code to use new protocol support functions")
Reviewed-by: Christian Schoenebeck 
Signed-off-by: Hangyu Hua 
Message-ID: <20231027030302.11927-1-hbh25y@gmail.com>
Signed-off-by: Dominique Martinet

9p: v9fs_listxattr: fix %s null argument warning

2023-10-25T22:05:52+00:00

W=1 warns about null argument to kprintf:
In file included from fs/9p/xattr.c:12:
In function ‘v9fs_xattr_get’,
    inlined from ‘v9fs_listxattr’ at fs/9p/xattr.c:142:9:
include/net/9p/9p.h:55:2: error: ‘%s’ directive argument is null
[-Werror=format-overflow=]
   55 |  _p9_debug(level, __func__, fmt, ##__VA_ARGS__)
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Use an empty string instead of :
 - this is ok 9p-wise because p9pdu_vwritef serializes a null string
and an empty string the same way (one '0' word for length)
 - since this degrades the print statements, add new single quotes for
xattr's name delimter (Old: "file = (null)", new: "file = ''")

Link: https://lore.kernel.org/r/20231008060138.517057-1-suhui@nfschina.com
Suggested-by: Su Hui 
Signed-off-by: Dominique Martinet 
Acked-by: Christian Schoenebeck 
Message-ID: <20231025103445.1248103-2-asmadeus@codewreck.org>

9p: remove dead stores (variable set again without being read)

2023-07-20T19:14:50+00:00

The 9p code for some reason used to initialize variables outside of the
declaration, e.g. instead of just initializing the variable like this:

int retval = 0

We would be doing this:

int retval;
retval = 0;

This is perfectly fine and the compiler will just optimize dead stores
anyway, but scan-build seems to think this is a problem and there are
many of these warnings making the output of scan-build full of such
warnings:
fs/9p/vfs_inode.c:916:2: warning: Value stored to 'retval' is never read [deadcode.DeadStores]
        retval = 0;
        ^        ~

I have no strong opinion here, but if we want to regularly run
scan-build we should fix these just to silence the messages.

I've confirmed these all are indeed ok to remove.

Reviewed-by: Simon Horman 
Signed-off-by: Dominique Martinet 
Signed-off-by: Eric Van Hensbergen

9p: Add additional debug flags and open modes

2023-03-27T02:33:48+00:00

Add some additional debug flags to assist with debugging
cache changes.  Also add some additional open modes so we
can track cache state in fids more directly.

Signed-off-by: Eric Van Hensbergen

net/9p: fix bug in client create for .L

2023-02-24T13:42:40+00:00

We are supposed to set fid->mode to reflect the flags
that were used to open the file.  We were actually setting
it to the creation mode which is the default perms of the
file not the flags the file was opened with.

Signed-off-by: Eric Van Hensbergen 
Reviewed-by: Dominique Martinet

net/9p: Adjust maximum MSIZE to account for p9 header

2023-02-23T22:39:36+00:00

Add maximum p9 header size to MSIZE to make sure we can
have page aligned data.

Signed-off-by: Eric Van Hensbergen 
Reviewed-by: Dominique Martinet

Merge tag '9p-for-6.2-rc1' of https://github.com/martinetd/linux

2022-12-23T19:39:18+00:00

Pull 9p updates from Dominique Martinet:

 - improve p9_check_errors to check buffer size instead of msize when
   possible (e.g. not zero-copy)

 - some more syzbot and KCSAN fixes

 - minor headers include cleanup

* tag '9p-for-6.2-rc1' of https://github.com/martinetd/linux:
  9p/client: fix data race on req->status
  net/9p: fix response size check in p9_check_errors()
  net/9p: distinguish zero-copy requests
  9p/xen: do not memcpy header into req->rc
  9p: set req refcount to zero to avoid uninitialized usage
  9p/net: Remove unneeded idr.h #include
  9p/fs: Remove unneeded idr.h #include

9p/client: fix data race on req->status

2022-12-13T04:02:15+00:00

KCSAN reported a race between writing req->status in p9_client_cb and
accessing it in p9_client_rpc's wait_event.

Accesses to req itself is protected by the data barrier (writing req
fields, write barrier, writing status // reading status, read barrier,
reading other req fields), but status accesses themselves apparently
also must be annotated properly with WRITE_ONCE/READ_ONCE when we
access it without locks.

Follows:
 - error paths writing status in various threads all can notify
p9_client_rpc, so these all also need WRITE_ONCE
 - there's a similar read loop in trans_virtio for zc case that also
needs READ_ONCE
 - other reads in trans_fd should be protected by the trans_fd lock and
lists state machine, as corresponding writers all are within trans_fd
and should be under the same lock. If KCSAN complains on them we likely
will have something else to fix as well, so it's better to leave them
unmarked and look again if required.

Link: https://lkml.kernel.org/r/20221205124756.426350-1-asmadeus@codewreck.org
Reported-by: Naresh Kamboju 
Suggested-by: Marco Elver 
Acked-by: Marco Elver 
Reviewed-by: Christian Schoenebeck 
Signed-off-by: Dominique Martinet

net/9p: fix response size check in p9_check_errors()

2022-12-05T22:31:18+00:00

Since commit 60ece0833b6c ("net/9p: allocate appropriate reduced message
buffers") it is no longer appropriate to check server's response size
against msize. Check against the previously allocated buffer capacity
instead.

- Omit this size check entirely for zero-copy messages, as those always
  allocate 4k (P9_ZC_HDR_SZ) linear buffers which are not used for actual
  payload and can be much bigger than 4k.

- Replace p9_debug() by pr_err() to make sure this message is always
  printed in case this error is triggered.

- Add 9p message type to error message to ease investigation.

Link: https://lkml.kernel.org/r/e0edec84b1c80119ae937ce854b4f5f6dbe2d08c.1669144861.git.linux_oss@crudebyte.com
Signed-off-by: Christian Schoenebeck 
Tested-by: Stefano Stabellini 
Reported-by: kernel test robot 
Signed-off-by: Dominique Martinet

net/9p: distinguish zero-copy requests

2022-12-05T22:30:55+00:00

Add boolean `zc` member to struct p9_fcall to distinguish zero-copy
messages (not using the linear `sdata` buffer for message payload) from
regular messages (which do copy message payload to `sdata` before being
further processed).

This new member is appended to end of structure to avoid inserting huge
padding in generated layout.

Link: https://lkml.kernel.org/r/8f2a5c12a446c3b544da64e0b1550e1fb2d6f972.1669144861.git.linux_oss@crudebyte.com
Signed-off-by: Christian Schoenebeck 
Tested-by: Stefano Stabellini 
Signed-off-by: Dominique Martinet