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Eric Dumazet 10f3b29c65 bpf, arm64: Clear prog->jited_len along prog->jited
syzbot reported an illegal copy_to_user() attempt
from bpf_prog_get_info_by_fd() [1]

There was no repro yet on this bug, but I think
that commit 0aef499f31 ("mm/usercopy: Detect vmalloc overruns")
is exposing a prior bug in bpf arm64.

bpf_prog_get_info_by_fd() looks at prog->jited_len
to determine if the JIT image can be copied out to user space.

My theory is that syzbot managed to get a prog where prog->jited_len
has been set to 43, while prog->bpf_func has ben cleared.

It is not clear why copy_to_user(uinsns, NULL, ulen) is triggering
this particular warning.

I thought find_vma_area(NULL) would not find a vm_struct.
As we do not hold vmap_area_lock spinlock, it might be possible
that the found vm_struct was garbage.

[1]
usercopy: Kernel memory exposure attempt detected from vmalloc (offset 792633534417210172, size 43)!
kernel BUG at mm/usercopy.c:101!
Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 25002 Comm: syz-executor.1 Not tainted 5.18.0-syzkaller-10139-g8291eaafed36 #0
Hardware name: linux,dummy-virt (DT)
pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : usercopy_abort+0x90/0x94 mm/usercopy.c:101
lr : usercopy_abort+0x90/0x94 mm/usercopy.c:89
sp : ffff80000b773a20
x29: ffff80000b773a30 x28: faff80000b745000 x27: ffff80000b773b48
x26: 0000000000000000 x25: 000000000000002b x24: 0000000000000000
x23: 00000000000000e0 x22: ffff80000b75db67 x21: 0000000000000001
x20: 000000000000002b x19: ffff80000b75db3c x18: 00000000fffffffd
x17: 2820636f6c6c616d x16: 76206d6f72662064 x15: 6574636574656420
x14: 74706d6574746120 x13: 2129333420657a69 x12: 73202c3237313031
x11: 3237313434333533 x10: 3336323937207465 x9 : 657275736f707865
x8 : ffff80000a30c550 x7 : ffff80000b773830 x6 : ffff80000b773830
x5 : 0000000000000000 x4 : ffff00007fbbaa10 x3 : 0000000000000000
x2 : 0000000000000000 x1 : f7ff000028fc0000 x0 : 0000000000000064
Call trace:
 usercopy_abort+0x90/0x94 mm/usercopy.c:89
 check_heap_object mm/usercopy.c:186 [inline]
 __check_object_size mm/usercopy.c:252 [inline]
 __check_object_size+0x198/0x36c mm/usercopy.c:214
 check_object_size include/linux/thread_info.h:199 [inline]
 check_copy_size include/linux/thread_info.h:235 [inline]
 copy_to_user include/linux/uaccess.h:159 [inline]
 bpf_prog_get_info_by_fd.isra.0+0xf14/0xfdc kernel/bpf/syscall.c:3993
 bpf_obj_get_info_by_fd+0x12c/0x510 kernel/bpf/syscall.c:4253
 __sys_bpf+0x900/0x2150 kernel/bpf/syscall.c:4956
 __do_sys_bpf kernel/bpf/syscall.c:5021 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5019 [inline]
 __arm64_sys_bpf+0x28/0x40 kernel/bpf/syscall.c:5019
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x48/0x114 arch/arm64/kernel/syscall.c:52
 el0_svc_common.constprop.0+0x44/0xec arch/arm64/kernel/syscall.c:142
 do_el0_svc+0xa0/0xc0 arch/arm64/kernel/syscall.c:206
 el0_svc+0x44/0xb0 arch/arm64/kernel/entry-common.c:624
 el0t_64_sync_handler+0x1ac/0x1b0 arch/arm64/kernel/entry-common.c:642
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:581
Code: aa0003e3 d00038c0 91248000 97fff65f (d4210000)

Fixes: db496944fd ("bpf: arm64: add JIT support for multi-function programs")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20220531215113.1100754-1-eric.dumazet@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-06-07 10:40:53 -07:00
Documentation Networking fixes for 5.19-rc1, including fixes from bpf, and netfilter. 2022-06-02 12:50:16 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
arch bpf, arm64: Clear prog->jited_len along prog->jited 2022-06-07 10:40:53 -07:00
block Page cache changes for 5.19 2022-05-24 19:55:07 -07:00
certs Kbuild updates for v5.19 2022-05-26 12:09:50 -07:00
crypto This update includes the following changes: 2022-05-27 18:06:49 -07:00
drivers stmmac: intel: Fix an error handling path in intel_eth_pci_probe() 2022-06-07 11:56:29 +02:00
fs A big pile of assorted fixes and improvements for the filesystem with 2022-06-02 08:59:39 -07:00
include Networking fixes for 5.19-rc1, including fixes from bpf, and netfilter. 2022-06-02 12:50:16 -07:00
init RISC-V Patches for the 5.19 Merge Window, Part 1 2022-05-31 14:10:54 -07:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-05-09 18:29:21 -07:00
kernel Networking fixes for 5.19-rc1, including fixes from bpf, and netfilter. 2022-06-02 12:50:16 -07:00
lib assoc_array: Fix BUG_ON during garbage collect 2022-06-01 18:29:06 -07:00
mm RISC-V Patches for the 5.19 Merge Window, Part 1 2022-05-31 14:10:54 -07:00
net af_unix: Fix a data-race in unix_dgram_peer_wake_me(). 2022-06-07 12:07:46 +02:00
samples drm for 5.19-rc1 2022-05-25 16:18:27 -07:00
scripts Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
security linux-kselftest-kunit-5.19-rc1 2022-05-25 11:32:53 -07:00
sound m68knommu: changes for linux 5.19 2022-05-30 10:56:18 -07:00
tools selftests net: fix bpf build error 2022-06-07 13:19:51 +02:00
usr Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
virt VFIO updates for v5.19-rc1 2022-06-01 13:49:15 -07:00
.clang-format clang-format: Fix space after for_each macros 2022-05-20 19:27:16 +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 kbuild: split the second line of *.mod into *.usyms 2022-05-08 03:16:59 +09:00
.mailmap MAINTAINERS: Update Lorenzo Pieralisi's email address 2022-05-31 15:06:19 -05:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
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 pci-v5.19-fixes-1 2022-06-02 12:11:25 -07:00
Makefile Kbuild updates for v5.19 2022-05-26 12:09:50 -07:00
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.