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John Fastabend 218d747a41 bpf, sockmap: Fix double bpf_prog_put on error case in map_link 
sock_map_link() is called to update a sockmap entry with a sk. But, if the
sock_map_init_proto() call fails then we return an error to the map_update
op against the sockmap. In the error path though we need to cleanup psock
and dec the refcnt on any programs associated with the map, because we
refcnt them early in the update process to ensure they are pinned for the
psock. (This avoids a race where user deletes programs while also updating
the map with new socks.)

In current code we do the prog refcnt dec explicitely by calling
bpf_prog_put() when the program was found in the map. But, after commit
'38207a5e81' in this error path we've already done the prog to psock
assignment so the programs have a reference from the psock as well. This
then causes the psock tear down logic, invoked by sk_psock_put() in the
error path, to similarly call bpf_prog_put on the programs there.

To be explicit this logic does the prog->psock assignment:

  if (msg_*)
    psock_set_prog(...)

Then the error path under the out_progs label does a similar check and
dec with:

  if (msg_*)
     bpf_prog_put(...)

And the teardown logic sk_psock_put() does ...

  psock_set_prog(msg_*, NULL)

... triggering another bpf_prog_put(...). Then KASAN gives us this splat,
found by syzbot because we've created an inbalance between bpf_prog_inc and
bpf_prog_put calling put twice on the program.

  BUG: KASAN: vmalloc-out-of-bounds in __bpf_prog_put kernel/bpf/syscall.c:1812 [inline]
  BUG: KASAN: vmalloc-out-of-bounds in __bpf_prog_put kernel/bpf/syscall.c:1812 [inline] kernel/bpf/syscall.c:1829
  BUG: KASAN: vmalloc-out-of-bounds in bpf_prog_put+0x8c/0x4f0 kernel/bpf/syscall.c:1829 kernel/bpf/syscall.c:1829
  Read of size 8 at addr ffffc90000e76038 by task syz-executor020/3641

To fix clean up error path so it doesn't try to do the bpf_prog_put in the
error path once progs are assigned then it relies on the normal psock
tear down logic to do complete cleanup.

For completness we also cover the case whereh sk_psock_init_strp() fails,
but this is not expected because it indicates an incorrect socket type
and should be caught earlier.

Fixes: 38207a5e81 ("bpf, sockmap: Attach map progs to psock early for feature probes")
Reported-by: syzbot+bb73e71cf4b8fd376a4f@syzkaller.appspotmail.com
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220104214645.290900-1-john.fastabend@gmail.com
History 2022-01-05 20:43:08 +01:00
arch bpf, arm64: Use emit_addr_mov_i64() for BPF_PSEUDO_FUNC 2022-01-05 20:43:08 +01:00
block block-5.16-2021-12-19 2021-12-19 12:38:53 -08:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Update to zstd-1.4.10 2021-11-13 15:32:30 -08:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-12-31 14:35:40 +00:00
drivers net: lan966x: Extend switchdev with mdb support 2022-01-05 11:25:13 +00:00
fs Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-12-31 14:35:40 +00:00
include net: mdio: add helpers to extract clause 45 regad and devad fields 2022-01-05 11:22:17 +00:00
init kbuild: Fix -Wimplicit-fallthrough=5 error for GCC 5.x and 6.x 2021-11-14 18:59:49 -08:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-11-20 10:35:54 -08:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-12-31 14:35:40 +00:00
lib lib: objagg: Use the bitmap API when applicable 2021-12-24 14:54:29 -08:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm/hwpoison: clear MF_COUNT_INCREASED before retrying get_any_page() 2021-12-25 12:20:56 -08:00
net bpf, sockmap: Fix double bpf_prog_put on error case in map_link 2022-01-05 20:43:08 +01:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-12-31 14:35:40 +00:00
scripts recordmcount.pl: fix typo in s390 mcount regex 2021-12-24 10:20:12 +01:00
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-12-31 14:35:40 +00:00
sound sound fixes for 5.16-rc7 2021-12-23 09:55:58 -08:00
tools bpf/selftests: Fix namespace mount setup in tc_redirect 2022-01-05 13:35:18 +01:00
usr initramfs: Check timestamp to prevent broken cpio archive 2021-10-24 13:48:40 +09:00
virt KVM: downgrade two BUG_ONs to WARN_ON_ONCE 2021-11-26 06:43:28 -05:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: update email address for Guo Ren 2021-12-10 17:10:55 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-12-30 12:12:12 -08:00
Makefile Linux 5.16-rc7 2021-12-26 13:17:17 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -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.

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.