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kernel test robot reported the splat below. [0] Before commitfed176bf31("net: Add ops_undo_single for module load/unload."), if CONFIG_NET_NS=n, ops was linked to pernet_list only when init_net had not been initialised, and ops was unlinked from pernet_list only under the same condition. Let's say an ops is loaded before the init_net setup but unloaded after that. Then, the ops remains in pernet_list, which seems odd. The cited commit added ops_undo_single(), which calls list_add() for ops to link it to a temporary list, so a minor change was added to __register_pernet_operations() and __unregister_pernet_operations() under CONFIG_NET_NS=n to avoid the pernet_list corruption. However, the corruption must have been left as is. When CONFIG_NET_NS=n, pernet_list was used to keep ops registered before the init_net setup, and after that, pernet_list was not used at all. This was because some ops annotated with __net_initdata are cleared out of memory at some point during boot. Then, such ops is initialised by POISON_FREE_INITMEM (0xcc), resulting in that ops->list.{next,prev} suddenly switches from a valid pointer to a weird value, 0xcccccccccccccccc. To avoid such wild memory access, let's allow the pernet_list corruption for CONFIG_NET_NS=n. [0]: Oops: general protection fault, probably for non-canonical address 0xf999959999999999: 0000 [#1] SMP KASAN NOPTI KASAN: maybe wild-memory-access in range [0xccccccccccccccc8-0xcccccccccccccccf] CPU: 2 UID: 0 PID: 346 Comm: modprobe Not tainted 6.15.0-rc1-00294-ga4cba7e98e35 #85 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 RIP: 0010:__list_add_valid_or_report (lib/list_debug.c:32) Code: 48 c1 ea 03 80 3c 02 00 0f 85 5a 01 00 00 49 39 74 24 08 0f 85 83 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 f2 48 c1 ea 03 <80> 3c 02 00 0f 85 1f 01 00 00 4c 39 26 0f 85 ab 00 00 00 4c 39 ee RSP: 0018:ff11000135b87830 EFLAGS: 00010a07 RAX: dffffc0000000000 RBX: ffffffffc02223c0 RCX: ffffffff8406fcc2 RDX: 1999999999999999 RSI: cccccccccccccccc RDI: ffffffffc02223c0 RBP: ffffffff86064e40 R08: 0000000000000001 R09: fffffbfff0a9f5b5 R10: ffffffff854fadaf R11: 676552203a54454e R12: ffffffff86064e40 R13: ffffffffc02223c0 R14: ffffffff86064e48 R15: 0000000000000021 FS: 00007f6fb0d9e1c0(0000) GS:ff11000858ea0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f6fb0eda580 CR3: 0000000122fec005 CR4: 0000000000771ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: <TASK> register_pernet_operations (./include/linux/list.h:150 (discriminator 5) ./include/linux/list.h:183 (discriminator 5) net/core/net_namespace.c:1315 (discriminator 5) net/core/net_namespace.c:1359 (discriminator 5)) register_pernet_subsys (net/core/net_namespace.c:1401) inet6_init (net/ipv6/af_inet6.c:535) ipv6 do_one_initcall (init/main.c:1257) do_init_module (kernel/module/main.c:2942) load_module (kernel/module/main.c:3409) init_module_from_file (kernel/module/main.c:3599) idempotent_init_module (kernel/module/main.c:3611) __x64_sys_finit_module (./include/linux/file.h:62 ./include/linux/file.h:83 kernel/module/main.c:3634 kernel/module/main.c:3621 kernel/module/main.c:3621) do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) RIP: 0033:0x7f6fb0df7e5d Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 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 8b 0d 73 9f 1b 00 f7 d8 64 89 01 48 RSP: 002b:00007fffdc6a8968 EFLAGS: 00000246 ORIG_RAX: 0000000000000139 RAX: ffffffffffffffda RBX: 000055b535721b70 RCX: 00007f6fb0df7e5d RDX: 0000000000000000 RSI: 000055b51e44aa2a RDI: 0000000000000004 RBP: 0000000000040000 R08: 0000000000000000 R09: 000055b535721b30 R10: 0000000000000004 R11: 0000000000000246 R12: 000055b51e44aa2a R13: 000055b535721bf0 R14: 000055b5357220b0 R15: 0000000000000000 </TASK> Modules linked in: ipv6(+) crc_ccitt Fixes:fed176bf31("net: Add ops_undo_single for module load/unload.") Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202504181511.1c3f23e4-lkp@intel.com Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Link: https://patch.msgid.link/20250418215025.87871-1-kuniyu@amazon.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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.