Re: [syzbot] [net?] WARNING in __virt_to_phys (6)

On Mon, Aug 10, 2026 at 5:24 PM syzbot
<[email protected]> wrote:
>
> Hello,
>
> syzbot found 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=134277b9580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=ccf4bea59f67007
> dashboard link: https://syzkaller.appspot.com/bug?extid=204eda57286574703583
> compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
> userspace arch: arm64
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> 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]
>
> ------------[ cut here ]------------
> virt_to_phys used for non-linear address: 00000000b1de4396 (0x17ffffe791001021)
> WARNING: arch/arm64/mm/physaddr.c:15 at __virt_to_phys+0xe8/0x130 arch/arm64/mm/physaddr.c:12, CPU#0: dhcpcd/4400
> Modules linked in:
> CPU: 0 UID: 100 PID: 4400 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
> pstate: 63400005 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
> pc : __virt_to_phys+0xe8/0x130 arch/arm64/mm/physaddr.c:12
> lr : __virt_to_phys+0xe8/0x130 arch/arm64/mm/physaddr.c:12
> sp : ffff8000997e72b0
> x29: ffff8000997e72b0 x28: ffff800088b0b6a0 x27: ffff0000c7228000
> x26: 17ffffe791001021 x25: 0000000000000204 x24: ffffc1ffc0000000
> x23: ffff80008869e000 x22: 000f600000000000 x21: 000000000000002d
> x20: 180fffe791001021 x19: 17ffffe791001021 x18: 0000000000000000
> x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
> x14: 0000000000000001 x13: 0000000000000001 x12: 0000000000000000
> x11: 0000000000000000 x10: 0000000000000002 x9 : b196a926009aaa00
> x8 : b196a926009aaa00 x7 : ffff80008048e080 x6 : 0000000000000000
> x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff8000802f8070
> x2 : 0000000100000000 x1 : ffff0000c7228000 x0 : 0000000000000000
> Call trace:
>  __virt_to_phys+0xe8/0x130 arch/arm64/mm/physaddr.c:12 (P)
>  virt_to_phys arch/arm64/include/asm/memory.h:369 [inline]
>  virt_to_pfn arch/arm64/include/asm/memory.h:383 [inline]
>  virt_to_slab mm/slab.h:193 [inline]
>  qlink_to_cache mm/kasan/quarantine.c:131 [inline]
>  qlist_free_all+0x58/0x120 mm/kasan/quarantine.c:176

It seems something (UAF? OOB-write?) corrupted KASAN metadata,
not an issue in AF_UNIX.


>  kasan_quarantine_reduce+0x118/0x124 mm/kasan/quarantine.c:286
>  __kasan_kmalloc+0x2c/0xb4 mm/kasan/common.c:406
>  kasan_kmalloc include/linux/kasan.h:263 [inline]
>  __do_kmalloc_node mm/slub.c:5334 [inline]
>  __kmalloc_node_track_caller_noprof+0x434/0x6d4 mm/slub.c:5471
>  kmalloc_reserve+0x118/0x214 net/core/skbuff.c:637
>  __alloc_skb+0x230/0x610 net/core/skbuff.c:715
>  alloc_skb include/linux/skbuff.h:1384 [inline]
>  alloc_skb_with_frags+0xb8/0x690 net/core/skbuff.c:6769
>  sock_alloc_send_pskb+0x740/0x850 net/core/sock.c:3013
>  unix_dgram_sendmsg+0x434/0x1078 net/unix/af_unix.c:2136
>  unix_seqpacket_sendmsg+0x108/0x1d0 net/unix/af_unix.c:2537
>  sock_sendmsg_nosec net/socket.c:775 [inline]
>  __sock_sendmsg+0xc8/0x17c net/socket.c:790
>  sock_write_iter+0x220/0x310 net/socket.c:1241
>  new_sync_write fs/read_write.c:595 [inline]
>  vfs_write+0x51c/0xa0c fs/read_write.c:687
>  ksys_write+0x12c/0x228 fs/read_write.c:739
>  __do_sys_write fs/read_write.c:750 [inline]
>  __se_sys_write fs/read_write.c:747 [inline]
>  __arm64_sys_write+0x84/0x98 fs/read_write.c:747
>  __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
>  invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
>  el0_svc_common+0x19c/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
> irq event stamp: 345484
> hardirqs last  enabled at (345483): [<ffff800080491644>] vprintk_store+0x924/0xb94 kernel/printk/printk.c:2385
> hardirqs last disabled at (345484): [<ffff8000868e6198>] el1_brk64+0x20/0x54 arch/arm64/kernel/entry-common.c:425
> softirqs last  enabled at (343926): [<ffff800084c14ca8>] __alloc_skb+0x1c0/0x610 net/core/skbuff.c:698
> softirqs last disabled at (343924): [<ffff800084c14c90>] local_bh_disable include/linux/bottom_half.h:20 [inline]
> softirqs last disabled at (343924): [<ffff800084c14c90>] __alloc_skb+0x1a8/0x610 net/core/skbuff.c:697
> ---[ end trace 0000000000000000 ]---
> Unable to handle kernel paging request at virtual address 005fffff638e0048
> Mem abort info:
>   ESR = 0x0000000096000004
>   EC = 0x25: DABT (current EL), IL = 32 bits
>   SET = 0, FnV = 0
>   EA = 0, S1PTW = 0
>   FSC = 0x04: level 0 translation fault
> Data abort info:
>   ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
>   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
>   GCS = 0, Overlay = 0, DirtyBit = 0
> [005fffff638e0048] address between user and kernel address ranges
> Internal error: Oops: 0000000096000004 [#1]  SMP
> Modules linked in:
> CPU: 0 UID: 100 PID: 4400 Comm: dhcpcd Tainted: G        W           syzkaller #0 PREEMPT
> Tainted: [W]=WARN
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
> pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
> pc : _compound_head include/linux/page-flags.h:226 [inline]
> pc : page_slab mm/slab.h:159 [inline]
> pc : virt_to_slab mm/slab.h:193 [inline]
> pc : qlink_to_cache mm/kasan/quarantine.c:131 [inline]
> pc : qlist_free_all+0x68/0x120 mm/kasan/quarantine.c:176
> lr : virt_to_phys arch/arm64/include/asm/memory.h:369 [inline]
> lr : virt_to_pfn arch/arm64/include/asm/memory.h:383 [inline]
> lr : virt_to_slab mm/slab.h:193 [inline]
> lr : qlink_to_cache mm/kasan/quarantine.c:131 [inline]
> lr : qlist_free_all+0x58/0x120 mm/kasan/quarantine.c:176
> sp : ffff8000997e72e0
> x29: ffff8000997e72e0 x28: ffff800088b0b6a0 x27: ffff0000c7228000
> x26: 17ffffe791001021 x25: 0000000000000204 x24: ffffc1ffc0000000
> x23: ffff80008869e000 x22: 17ffffe791001021 x21: ffffff1000040000
> x20: 0000000000000000 x19: ffff8000997e7330 x18: 0000000000000000
> x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
> x14: 0000000000000001 x13: 0000000000000001 x12: 0000000000000000
> x11: 0000000000000000 x10: 0000000000000002 x9 : 0000000000000000
> x8 : 005fffff638e0040 x7 : ffff80008048e080 x6 : 0000000000000000
> x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff8000802f8070
> x2 : 0000000100000000 x1 : ffff0000c7228000 x0 : 18007fe923801021
> Call trace:
>  virt_to_slab mm/slab.h:193 [inline] (P)
>  qlink_to_cache mm/kasan/quarantine.c:131 [inline] (P)
>  qlist_free_all+0x68/0x120 mm/kasan/quarantine.c:176 (P)
>  kasan_quarantine_reduce+0x118/0x124 mm/kasan/quarantine.c:286
>  __kasan_kmalloc+0x2c/0xb4 mm/kasan/common.c:406
>  kasan_kmalloc include/linux/kasan.h:263 [inline]
>  __do_kmalloc_node mm/slub.c:5334 [inline]
>  __kmalloc_node_track_caller_noprof+0x434/0x6d4 mm/slub.c:5471
>  kmalloc_reserve+0x118/0x214 net/core/skbuff.c:637
>  __alloc_skb+0x230/0x610 net/core/skbuff.c:715
>  alloc_skb include/linux/skbuff.h:1384 [inline]
>  alloc_skb_with_frags+0xb8/0x690 net/core/skbuff.c:6769
>  sock_alloc_send_pskb+0x740/0x850 net/core/sock.c:3013
>  unix_dgram_sendmsg+0x434/0x1078 net/unix/af_unix.c:2136
>  unix_seqpacket_sendmsg+0x108/0x1d0 net/unix/af_unix.c:2537
>  sock_sendmsg_nosec net/socket.c:775 [inline]
>  __sock_sendmsg+0xc8/0x17c net/socket.c:790
>  sock_write_iter+0x220/0x310 net/socket.c:1241
>  new_sync_write fs/read_write.c:595 [inline]
>  vfs_write+0x51c/0xa0c fs/read_write.c:687
>  ksys_write+0x12c/0x228 fs/read_write.c:739
>  __do_sys_write fs/read_write.c:750 [inline]
>  __se_sys_write fs/read_write.c:747 [inline]
>  __arm64_sys_write+0x84/0x98 fs/read_write.c:747
>  __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
>  invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
>  el0_svc_common+0x19c/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
> Code: d346fc08 927acd08 cb151908 8b180108 (f9400509)
> ---[ end trace 0000000000000000 ]---
> ----------------
> Code disassembly (best guess):
>    0:   d346fc08        lsr     x8, x0, #6
>    4:   927acd08        and     x8, x8, #0x3ffffffffffffc0
>    8:   cb151908        sub     x8, x8, x21, lsl #6
>    c:   8b180108        add     x8, x8, x24
> * 10:   f9400509        ldr     x9, [x8, #8] <-- trapping instruction
>
>
> ---
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