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Daniel Borkmann b165585795 bpf: implement dummy fops for bpf objects
syzkaller was able to trigger the following warning in
do_dentry_open():

  WARNING: CPU: 1 PID: 4508 at fs/open.c:778 do_dentry_open+0x4ad/0xe40 fs/open.c:778
  Kernel panic - not syncing: panic_on_warn set ...

  CPU: 1 PID: 4508 Comm: syz-executor867 Not tainted 4.17.0+ #90
  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
  Call Trace:
  [...]
   vfs_open+0x139/0x230 fs/open.c:908
   do_last fs/namei.c:3370 [inline]
   path_openat+0x1717/0x4dc0 fs/namei.c:3511
   do_filp_open+0x249/0x350 fs/namei.c:3545
   do_sys_open+0x56f/0x740 fs/open.c:1101
   __do_sys_openat fs/open.c:1128 [inline]
   __se_sys_openat fs/open.c:1122 [inline]
   __x64_sys_openat+0x9d/0x100 fs/open.c:1122
   do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
   entry_SYSCALL_64_after_hwframe+0x49/0xbe

Problem was that prog and map inodes in bpf fs did not
implement a dummy file open operation that would return an
error. The patch in do_dentry_open() checks whether f_ops
are present and if not bails out with an error. While this
may be fine, we really shouldn't be throwing a warning
though. Thus follow the model similar to bad_file_ops and
reject the request unconditionally with -EIO.

Fixes: b2197755b2 ("bpf: add support for persistent maps/progs")
Reported-by: syzbot+2e7fcab0f56fdbb330b8@syzkaller.appspotmail.com
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2018-06-08 10:58:48 -07:00
Documentation media updates for v4.18-rc1 2018-06-07 12:34:37 -07:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
arch net: in virtio_net_hdr only add VLAN_HLEN to csum_start if payload holds vlan 2018-06-07 16:15:38 -04:00
block Changes for 4.18: 2018-06-05 13:24:20 -07:00
certs certs/blacklist_nohashes.c: fix const confusion in certs blacklist 2018-02-21 15:35:43 -08:00
crypto - Introduce arithmetic overflow test helper functions (Rasmus) 2018-06-06 17:27:14 -07:00
drivers net: mscc: ocelot: Fix uninitialized error in ocelot_netdevice_event() 2018-06-07 16:54:39 -04:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs powerpc updates for 4.18 2018-06-07 10:23:33 -07:00
include Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2018-06-07 20:06:25 -04:00
init Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-06-06 18:39:49 -07:00
ipc Merge branch 'timers-2038-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-06-04 21:02:18 -07:00
kernel bpf: implement dummy fops for bpf objects 2018-06-08 10:58:48 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-06-06 18:39:49 -07:00
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net bpfilter: fix race in pipe access 2018-06-07 20:07:28 -04:00
samples samples/bpf: xdpsock: use skb Tx path for XDP_SKB 2018-06-05 15:48:57 +02:00
scripts powerpc updates for 4.18 2018-06-07 10:23:33 -07:00
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usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2018-06-04 15:23:48 -07:00
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.cocciconfig
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Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: add basic helper macros to scripts/Kconfig.include 2018-05-29 03:31:19 +09:00
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Makefile Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2018-06-06 18:39:49 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

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.