Re: [syzbot] [net?] KASAN: slab-out-of-bounds Read in copy_from_sockptr

syzbot has found a reproducer for the following issue on:

HEAD commit:    7235a3e71949 Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=1596dbb9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ccf4bea59f67007
dashboard link: https://syzkaller.appspot.com/bug?extid=6c98d6eb7aabb6b1ad39
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=167ecbb9580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fd45635beaae/disk-7235a3e7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d7d2e6507223/vmlinux-7235a3e7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b5b5d8de4cea/Image-7235a3e7.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]

==================================================================
BUG: KASAN: slab-out-of-bounds in copy_from_sockptr_offset include/linux/sockptr.h:49 [inline]
BUG: KASAN: slab-out-of-bounds in copy_from_sockptr+0x44/0x1b8 include/linux/sockptr.h:61
Read of size 84 at addr ffff0000d23743a0 by task syz.0.17/4925

CPU: 0 UID: 0 PID: 4925 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C)
 __dump_stack+0x30/0x40 lib/dump_stack.c:94
 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
 print_address_description+0xb0/0x238 mm/kasan/report.c:378
 print_report+0x68/0x84 mm/kasan/report.c:482
 kasan_report+0x8c/0xc4 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x17c/0x1ac mm/kasan/generic.c:200
 __asan_memcpy+0x3c/0x84 mm/kasan/shadow.c:105
 copy_from_sockptr_offset include/linux/sockptr.h:49 [inline]
 copy_from_sockptr+0x44/0x1b8 include/linux/sockptr.h:61
 vcc_setsockopt+0x174/0x450 net/atm/common.c:725
 pvc_setsockopt+0x84/0xb0 net/atm/pvc.c:72
 do_sock_setsockopt+0x1f0/0x330 net/socket.c:2368
 __sys_setsockopt+0x104/0x170 net/socket.c:2393
 __do_sys_setsockopt net/socket.c:2399 [inline]
 __se_sys_setsockopt net/socket.c:2396 [inline]
 __arm64_sys_setsockopt+0xc8/0xe4 net/socket.c:2396
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594

Allocated by task 4925:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x40/0x78 mm/kasan/common.c:78
 kasan_save_alloc_info+0x44/0x54 mm/kasan/generic.c:570
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x9c/0xb4 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5334 [inline]
 __kmalloc_noprof+0x340/0x6b8 mm/slub.c:5359
 _kmalloc_noprof include/linux/slab.h:992 [inline]
 __cgroup_bpf_run_filter_setsockopt+0x990/0xbbc kernel/bpf/cgroup.c:2103
 do_sock_setsockopt+0x2e8/0x330 net/socket.c:2350
 __sys_setsockopt+0x104/0x170 net/socket.c:2393
 __do_sys_setsockopt net/socket.c:2399 [inline]
 __se_sys_setsockopt net/socket.c:2396 [inline]
 __arm64_sys_setsockopt+0xc8/0xe4 net/socket.c:2396
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736
 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594

The buggy address belongs to the object at ffff0000d23743a0
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 0 bytes inside of
 allocated 4-byte region [ffff0000d23743a0, ffff0000d23743a4)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff0000d2374460 pfn:0x112374
flags: 0x5ffc00000000200(workingset|node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 05ffc00000000200 ffff0000c0001500 ffff0000c0000348 fffffdffc32f1f10
raw: ffff0000d2374460 0000000800800041 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000d2374280: 07 fc fc fc 07 fc fc fc 07 fc fc fc 07 fc fc fc
 ffff0000d2374300: 07 fc fc fc 07 fc fc fc 05 fc fc fc 05 fc fc fc
>ffff0000d2374380: fa fc fc fc 04 fc fc fc fa fc fc fc fa fc fc fc
                               ^
 ffff0000d2374400: fa fc fc fc 00 fc fc fc fa fc fc fc fa fc fc fc
 ffff0000d2374480: fa fc fc fc fa fc fc fc fa fc fc fc fa fc fc fc
==================================================================


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