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Filename Latest commit message Latest commit date
Arnd Bergmann 4bb8b65a04 xfs: fix string handling in label get/set functions
[sandeen: fix subject, avoid copy-out of uninit data in getlabel]

gcc-8 reports two warnings for the newly added getlabel/setlabel code:

fs/xfs/xfs_ioctl.c: In function 'xfs_ioc_getlabel':
fs/xfs/xfs_ioctl.c:1822:38: error: argument to 'sizeof' in 'strncpy' call is the same expression as the source; did you mean to use the size of the destination? [-Werror=sizeof-pointer-memaccess]
  strncpy(label, sbp->sb_fname, sizeof(sbp->sb_fname));
                                      ^
In function 'strncpy',
    inlined from 'xfs_ioc_setlabel' at /git/arm-soc/fs/xfs/xfs_ioctl.c:1863:2,
    inlined from 'xfs_file_ioctl' at /git/arm-soc/fs/xfs/xfs_ioctl.c:1918:10:
include/linux/string.h:254:9: error: '__builtin_strncpy' output may be truncated copying 12 bytes from a string of length 12 [-Werror=stringop-truncation]
  return __builtin_strncpy(p, q, size);

In both cases, part of the problem is that one of the strncpy()
arguments is a fixed-length character array with zero-padding rather
than a zero-terminated string. In the first one case, we also get an
odd warning about sizeof-pointer-memaccess, which doesn't seem right
(the sizeof is for an array that happens to be the same as the second
strncpy argument).

To work around the bogus warning, I use a plain 'XFSLABEL_MAX' for
the strncpy() length when copying the label in getlabel. For setlabel(),
using memcpy() with the correct length that is already known avoids
the second warning and is slightly simpler.

In a related issue, it appears that we accidentally skip the trailing
\0 when copying a 12-character label back to user space in getlabel().
Using the correct sizeof() argument here copies the extra character.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85602
Fixes: f7664b3197 ("xfs: implement online get/set fs label")
Cc: Eric Sandeen <sandeen@redhat.com>
Cc: Martin Sebor <msebor@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2018-06-06 14:17:53 -07:00
arch KVM fixes for v4.17-rc4 2018-05-06 05:46:29 -10:00
block block: add a lower-level bio_add_page interface 2018-06-01 18:37:32 -07:00
certs
crypto
Documentation fs: copy BTRFS_IOC_[SG]ET_FSLABEL to vfs 2018-05-16 08:50:16 -07:00
drivers dax: change bdev_dax_supported() to support boolean returns 2018-05-31 08:58:34 -07:00
firmware
fs xfs: fix string handling in label get/set functions 2018-06-06 14:17:53 -07:00
include fs: move page_cache_seek_hole_data to iomap.c 2018-06-01 18:37:33 -07:00
init
ipc
kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-05-06 05:35:23 -10:00
lib
LICENSES
mm mm: split ->readpages calls to avoid non-contiguous pages lists 2018-06-01 18:37:32 -07:00
net
samples
scripts Kbuild fixes for v4.17 2018-05-04 21:15:25 -10:00
security
sound
tools ACPI fix for 4.17-rc4 2018-05-04 05:43:33 -10:00
usr
virt KVM/arm fixes for 4.17, take #2 2018-05-05 23:05:31 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Kbuild fixes for v4.17 2018-05-04 21:15:25 -10:00
Makefile Linux 4.17-rc4 2018-05-06 16:57:38 -10:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.