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Kuniyuki Iwashima 5aa57d9f2d af_unix: Don't return OOB skb in manage_oob(). 
syzbot reported use-after-free in unix_stream_recv_urg(). [0]

The scenario is

  1. send(MSG_OOB)
  2. recv(MSG_OOB)
     -> The consumed OOB remains in recv queue
  3. send(MSG_OOB)
  4. recv()
     -> manage_oob() returns the next skb of the consumed OOB
     -> This is also OOB, but unix_sk(sk)->oob_skb is not cleared
  5. recv(MSG_OOB)
     -> unix_sk(sk)->oob_skb is used but already freed

The recent commit 8594d9b85c ("af_unix: Don't call skb_get() for OOB
skb.") uncovered the issue.

If the OOB skb is consumed and the next skb is peeked in manage_oob(),
we still need to check if the skb is OOB.

Let's do so by falling back to the following checks in manage_oob()
and add the test case in selftest.

Note that we need to add a similar check for SIOCATMARK.

[0]:
BUG: KASAN: slab-use-after-free in unix_stream_read_actor+0xa6/0xb0 net/unix/af_unix.c:2959
Read of size 4 at addr ffff8880326abcc4 by task syz-executor178/5235

CPU: 0 UID: 0 PID: 5235 Comm: syz-executor178 Not tainted 6.11.0-rc5-syzkaller-00742-gfbdaffe41adc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 unix_stream_read_actor+0xa6/0xb0 net/unix/af_unix.c:2959
 unix_stream_recv_urg+0x1df/0x320 net/unix/af_unix.c:2640
 unix_stream_read_generic+0x2456/0x2520 net/unix/af_unix.c:2778
 unix_stream_recvmsg+0x22b/0x2c0 net/unix/af_unix.c:2996
 sock_recvmsg_nosec net/socket.c:1046 [inline]
 sock_recvmsg+0x22f/0x280 net/socket.c:1068
 ____sys_recvmsg+0x1db/0x470 net/socket.c:2816
 ___sys_recvmsg net/socket.c:2858 [inline]
 __sys_recvmsg+0x2f0/0x3e0 net/socket.c:2888
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5360d6b4e9
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff29b3a458 EFLAGS: 00000246 ORIG_RAX: 000000000000002f
RAX: ffffffffffffffda RBX: 00007fff29b3a638 RCX: 00007f5360d6b4e9
RDX: 0000000000002001 RSI: 0000000020000640 RDI: 0000000000000003
RBP: 00007f5360dde610 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fff29b3a628 R14: 0000000000000001 R15: 0000000000000001
 </TASK>

Allocated by task 5235:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 unpoison_slab_object mm/kasan/common.c:312 [inline]
 __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:338
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook mm/slub.c:3988 [inline]
 slab_alloc_node mm/slub.c:4037 [inline]
 kmem_cache_alloc_node_noprof+0x16b/0x320 mm/slub.c:4080
 __alloc_skb+0x1c3/0x440 net/core/skbuff.c:667
 alloc_skb include/linux/skbuff.h:1320 [inline]
 alloc_skb_with_frags+0xc3/0x770 net/core/skbuff.c:6528
 sock_alloc_send_pskb+0x91a/0xa60 net/core/sock.c:2815
 sock_alloc_send_skb include/net/sock.h:1778 [inline]
 queue_oob+0x108/0x680 net/unix/af_unix.c:2198
 unix_stream_sendmsg+0xd24/0xf80 net/unix/af_unix.c:2351
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x221/0x270 net/socket.c:745
 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2597
 ___sys_sendmsg net/socket.c:2651 [inline]
 __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2680
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5235:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
 poison_slab_object+0xe0/0x150 mm/kasan/common.c:240
 __kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
 kasan_slab_free include/linux/kasan.h:184 [inline]
 slab_free_hook mm/slub.c:2252 [inline]
 slab_free mm/slub.c:4473 [inline]
 kmem_cache_free+0x145/0x350 mm/slub.c:4548
 unix_stream_read_generic+0x1ef6/0x2520 net/unix/af_unix.c:2917
 unix_stream_recvmsg+0x22b/0x2c0 net/unix/af_unix.c:2996
 sock_recvmsg_nosec net/socket.c:1046 [inline]
 sock_recvmsg+0x22f/0x280 net/socket.c:1068
 __sys_recvfrom+0x256/0x3e0 net/socket.c:2255
 __do_sys_recvfrom net/socket.c:2273 [inline]
 __se_sys_recvfrom net/socket.c:2269 [inline]
 __x64_sys_recvfrom+0xde/0x100 net/socket.c:2269
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8880326abc80
 which belongs to the cache skbuff_head_cache of size 240
The buggy address is located 68 bytes inside of
 freed 240-byte region [ffff8880326abc80, ffff8880326abd70)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x326ab
ksm flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xfdffffff(slab)
raw: 00fff00000000000 ffff88801eaee780 ffffea0000b7dc80 dead000000000003
raw: 0000000000000000 00000000800c000c 00000001fdffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 4686, tgid 4686 (udevadm), ts 32357469485, free_ts 28829011109
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1493
 prep_new_page mm/page_alloc.c:1501 [inline]
 get_page_from_freelist+0x2e4c/0x2f10 mm/page_alloc.c:3439
 __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4695
 __alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
 alloc_slab_page+0x5f/0x120 mm/slub.c:2321
 allocate_slab+0x5a/0x2f0 mm/slub.c:2484
 new_slab mm/slub.c:2537 [inline]
 ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3723
 __slab_alloc+0x58/0xa0 mm/slub.c:3813
 __slab_alloc_node mm/slub.c:3866 [inline]
 slab_alloc_node mm/slub.c:4025 [inline]
 kmem_cache_alloc_node_noprof+0x1fe/0x320 mm/slub.c:4080
 __alloc_skb+0x1c3/0x440 net/core/skbuff.c:667
 alloc_skb include/linux/skbuff.h:1320 [inline]
 alloc_uevent_skb+0x74/0x230 lib/kobject_uevent.c:289
 uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline]
 kobject_uevent_net_broadcast+0x2fd/0x580 lib/kobject_uevent.c:410
 kobject_uevent_env+0x57d/0x8e0 lib/kobject_uevent.c:608
 kobject_synth_uevent+0x4ef/0xae0 lib/kobject_uevent.c:207
 uevent_store+0x4b/0x70 drivers/base/bus.c:633
 kernfs_fop_write_iter+0x3a1/0x500 fs/kernfs/file.c:334
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0xa72/0xc90 fs/read_write.c:590
page last free pid 1 tgid 1 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1094 [inline]
 free_unref_page+0xd22/0xea0 mm/page_alloc.c:2612
 kasan_depopulate_vmalloc_pte+0x74/0x90 mm/kasan/shadow.c:408
 apply_to_pte_range mm/memory.c:2797 [inline]
 apply_to_pmd_range mm/memory.c:2841 [inline]
 apply_to_pud_range mm/memory.c:2877 [inline]
 apply_to_p4d_range mm/memory.c:2913 [inline]
 __apply_to_page_range+0x8a8/0xe50 mm/memory.c:2947
 kasan_release_vmalloc+0x9a/0xb0 mm/kasan/shadow.c:525
 purge_vmap_node+0x3e3/0x770 mm/vmalloc.c:2208
 __purge_vmap_area_lazy+0x708/0xae0 mm/vmalloc.c:2290
 _vm_unmap_aliases+0x79d/0x840 mm/vmalloc.c:2885
 change_page_attr_set_clr+0x2fe/0xdb0 arch/x86/mm/pat/set_memory.c:1881
 change_page_attr_set arch/x86/mm/pat/set_memory.c:1922 [inline]
 set_memory_nx+0xf2/0x130 arch/x86/mm/pat/set_memory.c:2110
 free_init_pages arch/x86/mm/init.c:924 [inline]
 free_kernel_image_pages arch/x86/mm/init.c:943 [inline]
 free_initmem+0x79/0x110 arch/x86/mm/init.c:970
 kernel_init+0x31/0x2b0 init/main.c:1476
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Memory state around the buggy address:
 ffff8880326abb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880326abc00: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc
>ffff8880326abc80: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff8880326abd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
 ffff8880326abd80: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb

Fixes: 93c99f21db ("af_unix: Don't stop recv(MSG_DONTWAIT) if consumed OOB skb is at the head.")
Reported-by: syzbot+8811381d455e3e9ec788@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8811381d455e3e9ec788
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20240905193240.17565-5-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-09-09 17:14:27 -07:00
arch ARM fix for v6.11 2024-09-04 09:17:33 -07:00
block block: fix detection of unsupported WRITE SAME in blkdev_issue_write_zeroes 2024-08-28 08:49:25 -06:00
certs kbuild: use $(src) instead of $(srctree)/$(src) for source directory 2024-05-10 04:34:52 +09:00
crypto crypto: testmgr - generate power-of-2 lengths more often 2024-07-13 11:50:28 +12:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2024-09-05 20:37:20 -07:00
drivers linux-can-next-for-6.12-20240909 2024-09-09 17:11:05 -07:00
fs Tracing fixes for 6.11: 2024-09-05 16:29:41 -07:00
include net: remove dev_pick_tx_cpu_id() 2024-09-09 16:53:38 -07:00
init Rust fixes for v6.11 2024-08-16 11:24:06 -07:00
io_uring io_uring/kbuf: return correct iovec count from classic buffer peek 2024-08-30 10:45:54 -06:00
ipc sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
kernel Tracing fixes for 6.11: 2024-09-05 16:29:41 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2024-09-05 20:37:20 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm vfs-6.11-rc7.fixes 2024-09-04 09:33:57 -07:00
net af_unix: Don't return OOB skb in manage_oob(). 2024-09-09 17:14:27 -07:00
rust Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2024-09-05 20:37:20 -07:00
samples treewide: remove unnecessary <linux/version.h> inclusion 2024-08-12 18:36:44 +09:00
scripts scripts: fix gfp-translate after ___GFP_*_BITS conversion to an enum 2024-09-01 17:59:01 -07:00
security Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging 2024-09-01 09:18:48 +12:00
sound sound fixes for 6.11-rc6 2024-08-28 06:24:22 +12:00
tools af_unix: Don't return OOB skb in manage_oob(). 2024-09-09 17:14:27 -07:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt KVM: x86: Disallow read-only memslots for SEV-ES and SEV-SNP (and TDX) 2024-08-14 12:28:24 -04:00
.clang-format Docs: Move clang-format from process/ to dev-tools/ 2024-06-26 16:36:00 -06:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore .gitignore: add .gcda files 2024-08-09 13:18:46 +01:00
.mailmap Rust fixes for v6.11 (2nd) 2024-09-05 16:35:57 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS tracing: Update of MAINTAINERS and CREDITS file 2024-07-18 14:08:42 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: Add the rtase ethernet driver entry 2024-09-05 22:02:39 -07:00
Makefile Rust fixes for v6.11 (2nd) 2024-09-05 16:35:57 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -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 reStructuredText 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.