Extracting prog: 2m36.08513222s
Minimizing prog: 11m45.803623422s
Simplifying prog options: 0s
Extracting C: 1m0.088854279s
Simplifying C: 9m54.493524867s


extracting reproducer from 1 programs
testing a last program of every proc
single: executing 1 programs separately with timeout 30s
testing program (duration=30s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$auto_proc_reg_file_ops_compat_inode-poll$auto-write$auto_msr_fops_msr
detailed listing:
executing program 0:
r0 = openat$auto_proc_reg_file_ops_compat_inode(0xffffffffffffff9c, &(0x7f0000000080)='/proc/thread-self/net/afs/rootcell\x00', 0x48041, 0x0)
poll$auto(&(0x7f0000000000)={<r1=>r0, 0x435, 0x2}, 0x0, 0x3)
write$auto_msr_fops_msr(r1, &(0x7f0000000200)="2cdde02c4a23d0bfa2f142fd75faff3d3af64fae3492be4393a7636f05a6c6971625de4c842b45f72910474ce639310135b9a02584e8bb6e95de80ed32512b496df8053e2b6c4373d9ca8ad0d080f779f9be749540b84ba93ab97cf87fcb5e56656076df7458cca87339307dba5397c890b3e0c2eab613b78b0c2941fdb09446876a375cd4dbb3d09fa959514f82fa3eddee04a5067d42403657d10b2c37", 0x9e)

program crashed: BUG: unable to handle kernel paging request in afs_put_vlserverlist
single: successfully extracted reproducer
found reproducer with 3 syscalls
minimizing guilty program
testing program (duration=1m3.658765314s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$auto_proc_reg_file_ops_compat_inode-poll$auto
detailed listing:
executing program 0:
r0 = openat$auto_proc_reg_file_ops_compat_inode(0xffffffffffffff9c, &(0x7f0000000080)='/proc/thread-self/net/afs/rootcell\x00', 0x48041, 0x0)
poll$auto(&(0x7f0000000000)={r0, 0x435, 0x2}, 0x0, 0x3)

program did not crash
testing program (duration=1m3.658765314s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$auto_proc_reg_file_ops_compat_inode-write$auto_msr_fops_msr
detailed listing:
executing program 0:
openat$auto_proc_reg_file_ops_compat_inode(0xffffffffffffff9c, &(0x7f0000000080)='/proc/thread-self/net/afs/rootcell\x00', 0x48041, 0x0)
write$auto_msr_fops_msr(0xffffffffffffffff, &(0x7f0000000200)="2cdde02c4a23d0bfa2f142fd75faff3d3af64fae3492be4393a7636f05a6c6971625de4c842b45f72910474ce639310135b9a02584e8bb6e95de80ed32512b496df8053e2b6c4373d9ca8ad0d080f779f9be749540b84ba93ab97cf87fcb5e56656076df7458cca87339307dba5397c890b3e0c2eab613b78b0c2941fdb09446876a375cd4dbb3d09fa959514f82fa3eddee04a5067d42403657d10b2c37", 0x9e)

program did not crash
testing program (duration=1m3.658765314s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): poll$auto-write$auto_msr_fops_msr
detailed listing:
executing program 0:
poll$auto(&(0x7f0000000000)={<r0=>0xffffffffffffffff, 0x435, 0x2}, 0x0, 0x3)
write$auto_msr_fops_msr(r0, &(0x7f0000000200)="2cdde02c4a23d0bfa2f142fd75faff3d3af64fae3492be4393a7636f05a6c6971625de4c842b45f72910474ce639310135b9a02584e8bb6e95de80ed32512b496df8053e2b6c4373d9ca8ad0d080f779f9be749540b84ba93ab97cf87fcb5e56656076df7458cca87339307dba5397c890b3e0c2eab613b78b0c2941fdb09446876a375cd4dbb3d09fa959514f82fa3eddee04a5067d42403657d10b2c37", 0x9e)

program did not crash
testing program (duration=1m3.658765314s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$auto_proc_reg_file_ops_compat_inode-poll$auto-write$auto_msr_fops_msr
detailed listing:
executing program 0:
r0 = openat$auto_proc_reg_file_ops_compat_inode(0xffffffffffffff9c, 0x0, 0x48041, 0x0)
poll$auto(&(0x7f0000000000)={<r1=>r0, 0x435, 0x2}, 0x0, 0x3)
write$auto_msr_fops_msr(r1, &(0x7f0000000200)="2cdde02c4a23d0bfa2f142fd75faff3d3af64fae3492be4393a7636f05a6c6971625de4c842b45f72910474ce639310135b9a02584e8bb6e95de80ed32512b496df8053e2b6c4373d9ca8ad0d080f779f9be749540b84ba93ab97cf87fcb5e56656076df7458cca87339307dba5397c890b3e0c2eab613b78b0c2941fdb09446876a375cd4dbb3d09fa959514f82fa3eddee04a5067d42403657d10b2c37", 0x9e)

program did not crash
testing program (duration=1m3.658765314s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$auto_proc_reg_file_ops_compat_inode-poll$auto-write$auto_msr_fops_msr
detailed listing:
executing program 0:
openat$auto_proc_reg_file_ops_compat_inode(0xffffffffffffff9c, &(0x7f0000000080)='/proc/thread-self/net/afs/rootcell\x00', 0x48041, 0x0)
poll$auto(0x0, 0x0, 0x3)
write$auto_msr_fops_msr(0xffffffffffffffff, &(0x7f0000000200)="2cdde02c4a23d0bfa2f142fd75faff3d3af64fae3492be4393a7636f05a6c6971625de4c842b45f72910474ce639310135b9a02584e8bb6e95de80ed32512b496df8053e2b6c4373d9ca8ad0d080f779f9be749540b84ba93ab97cf87fcb5e56656076df7458cca87339307dba5397c890b3e0c2eab613b78b0c2941fdb09446876a375cd4dbb3d09fa959514f82fa3eddee04a5067d42403657d10b2c37", 0x9e)

program did not crash
testing program (duration=1m3.658765314s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$auto_proc_reg_file_ops_compat_inode-poll$auto-write$auto_msr_fops_msr
detailed listing:
executing program 0:
r0 = openat$auto_proc_reg_file_ops_compat_inode(0xffffffffffffff9c, &(0x7f0000000080)='/proc/thread-self/net/afs/rootcell\x00', 0x48041, 0x0)
poll$auto(&(0x7f0000000000)={<r1=>r0, 0x435, 0x2}, 0x0, 0x3)
write$auto_msr_fops_msr(r1, 0x0, 0x0)

program did not crash
testing program (duration=1m3.658765314s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$auto_proc_reg_file_ops_compat_inode-poll$auto-write$auto_msr_fops_msr
detailed listing:
executing program 0:
r0 = openat$auto_proc_reg_file_ops_compat_inode(0xffffffffffffff9c, &(0x7f0000000080)='/proc/thread-self/net/afs/rootcell\x00', 0x48041, 0x0)
poll$auto(&(0x7f0000000000)={<r1=>r0, 0x435, 0x2}, 0x0, 0x3)
write$auto_msr_fops_msr(r1, &(0x7f0000000200), 0x0)

program did not crash
extracting C reproducer
testing compiled C program (duration=1m3.658765314s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$auto_proc_reg_file_ops_compat_inode-poll$auto-write$auto_msr_fops_msr
program crashed: BUG: unable to handle kernel paging request in afs_put_vlserverlist
simplifying C reproducer
testing compiled C program (duration=1m3.658765314s, {Threaded:false Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$auto_proc_reg_file_ops_compat_inode-poll$auto-write$auto_msr_fops_msr
program crashed: BUG: unable to handle kernel paging request in afs_put_vlserverlist
testing compiled C program (duration=1m3.658765314s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$auto_proc_reg_file_ops_compat_inode-poll$auto-write$auto_msr_fops_msr
program crashed: BUG: unable to handle kernel paging request in afs_put_vlserverlist
testing compiled C program (duration=1m3.658765314s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:true Sysctl:true Swap:false UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$auto_proc_reg_file_ops_compat_inode-poll$auto-write$auto_msr_fops_msr
program crashed: BUG: unable to handle kernel paging request in afs_put_vlserverlist
testing compiled C program (duration=1m3.658765314s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:false UseTmpDir:true HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$auto_proc_reg_file_ops_compat_inode-poll$auto-write$auto_msr_fops_msr
program crashed: BUG: unable to handle kernel paging request in afs_put_vlserverlist
testing compiled C program (duration=1m3.658765314s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:false UseTmpDir:false HandleSegv:true Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$auto_proc_reg_file_ops_compat_inode-poll$auto-write$auto_msr_fops_msr
program crashed: BUG: unable to handle kernel paging request in afs_put_vlserverlist
testing compiled C program (duration=1m3.658765314s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:false UseTmpDir:false HandleSegv:false Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$auto_proc_reg_file_ops_compat_inode-poll$auto-write$auto_msr_fops_msr
program crashed: BUG: unable to handle kernel paging request in afs_put_vlserverlist
testing compiled C program (duration=1m3.658765314s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:false Swap:false UseTmpDir:false HandleSegv:false Trace:false LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): openat$auto_proc_reg_file_ops_compat_inode-poll$auto-write$auto_msr_fops_msr
program crashed: BUG: unable to handle kernel paging request in afs_put_vlserverlist
reproducing took 25m16.471157587s
repro crashed as (corrupted=false):
kAFS: bad VL server IP address
BUG: unable to handle page fault for address: fffffffffffffffa
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD e186067 P4D e186067 PUD e188067 PMD 0 
Oops: Oops: 0002 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 5834 Comm: syz-executor362 Not tainted 6.15.0-rc1-syzkaller-00025-gbec7dcbc242c #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:arch_atomic_fetch_add arch/x86/include/asm/atomic.h:93 [inline]
RIP: 0010:raw_atomic_fetch_sub_release include/linux/atomic/atomic-arch-fallback.h:949 [inline]
RIP: 0010:atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:401 [inline]
RIP: 0010:__refcount_sub_and_test include/linux/refcount.h:389 [inline]
RIP: 0010:__refcount_dec_and_test include/linux/refcount.h:432 [inline]
RIP: 0010:refcount_dec_and_test include/linux/refcount.h:450 [inline]
RIP: 0010:afs_put_vlserverlist+0x3a/0x220 fs/afs/vl_list.c:67
Code: 53 48 83 ec 18 e8 e6 35 2f fe 48 85 ed 74 43 e8 dc 35 2f fe 4c 8d 65 10 be 04 00 00 00 bb ff ff ff ff 4c 89 e7 e8 76 ad 93 fe <f0> 0f c1 5d 10 31 ff 89 de e8 f8 30 2f fe 85 db 7e 29 e8 af 35 2f
RSP: 0018:ffffc90003e5fae0 EFLAGS: 00010246
RAX: 0000000000000001 RBX: 00000000ffffffff RCX: ffffffff838c071a
RDX: fffffc0000000000 RSI: 0000000000000004 RDI: fffffffffffffffa
RBP: ffffffffffffffea R08: 0000000000000001 R09: fffffbffffffffff
R10: fffffffffffffffd R11: 0000000000000001 R12: fffffffffffffffa
R13: ffffffffffffffea R14: ffff8880216ad700 R15: ffff888034ec2000
FS:  0000555561d3e380(0000) GS:ffff888124ab9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffa CR3: 000000007a922000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 afs_alloc_cell fs/afs/cell.c:218 [inline]
 afs_lookup_cell+0x12a5/0x1680 fs/afs/cell.c:264
 afs_cell_init+0x17a/0x380 fs/afs/cell.c:386
 afs_proc_rootcell_write+0x21f/0x290 fs/afs/proc.c:247
 proc_simple_write+0x114/0x1b0 fs/proc/generic.c:825
 pde_write fs/proc/inode.c:330 [inline]
 proc_reg_write+0x23d/0x330 fs/proc/inode.c:342
 vfs_write+0x25c/0x1180 fs/read_write.c:682
 ksys_write+0x12a/0x240 fs/read_write.c:736
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fab4ed8ba79
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 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:00007fff0c666448 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000200000000000 RCX: 00007fab4ed8ba79
RDX: 000000000000009e RSI: 0000200000000200 RDI: 0000000000000003
RBP: 00007fab4edfe5f0 R08: 0000000000000006 R09: 0000000000000006
R10: 0000000000000006 R11: 0000000000000246 R12: 0000000000000001
R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001
 </TASK>
Modules linked in:
CR2: fffffffffffffffa
---[ end trace 0000000000000000 ]---
RIP: 0010:arch_atomic_fetch_add arch/x86/include/asm/atomic.h:93 [inline]
RIP: 0010:raw_atomic_fetch_sub_release include/linux/atomic/atomic-arch-fallback.h:949 [inline]
RIP: 0010:atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:401 [inline]
RIP: 0010:__refcount_sub_and_test include/linux/refcount.h:389 [inline]
RIP: 0010:__refcount_dec_and_test include/linux/refcount.h:432 [inline]
RIP: 0010:refcount_dec_and_test include/linux/refcount.h:450 [inline]
RIP: 0010:afs_put_vlserverlist+0x3a/0x220 fs/afs/vl_list.c:67
Code: 53 48 83 ec 18 e8 e6 35 2f fe 48 85 ed 74 43 e8 dc 35 2f fe 4c 8d 65 10 be 04 00 00 00 bb ff ff ff ff 4c 89 e7 e8 76 ad 93 fe <f0> 0f c1 5d 10 31 ff 89 de e8 f8 30 2f fe 85 db 7e 29 e8 af 35 2f
RSP: 0018:ffffc90003e5fae0 EFLAGS: 00010246
RAX: 0000000000000001 RBX: 00000000ffffffff RCX: ffffffff838c071a
RDX: fffffc0000000000 RSI: 0000000000000004 RDI: fffffffffffffffa
RBP: ffffffffffffffea R08: 0000000000000001 R09: fffffbffffffffff
R10: fffffffffffffffd R11: 0000000000000001 R12: fffffffffffffffa
R13: ffffffffffffffea R14: ffff8880216ad700 R15: ffff888034ec2000
FS:  0000555561d3e380(0000) GS:ffff888124ab9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffa CR3: 000000007a922000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	53                   	push   %rbx
   1:	48 83 ec 18          	sub    $0x18,%rsp
   5:	e8 e6 35 2f fe       	call   0xfe2f35f0
   a:	48 85 ed             	test   %rbp,%rbp
   d:	74 43                	je     0x52
   f:	e8 dc 35 2f fe       	call   0xfe2f35f0
  14:	4c 8d 65 10          	lea    0x10(%rbp),%r12
  18:	be 04 00 00 00       	mov    $0x4,%esi
  1d:	bb ff ff ff ff       	mov    $0xffffffff,%ebx
  22:	4c 89 e7             	mov    %r12,%rdi
  25:	e8 76 ad 93 fe       	call   0xfe93ada0
* 2a:	f0 0f c1 5d 10       	lock xadd %ebx,0x10(%rbp) <-- trapping instruction
  2f:	31 ff                	xor    %edi,%edi
  31:	89 de                	mov    %ebx,%esi
  33:	e8 f8 30 2f fe       	call   0xfe2f3130
  38:	85 db                	test   %ebx,%ebx
  3a:	7e 29                	jle    0x65
  3c:	e8                   	.byte 0xe8
  3d:	af                   	scas   %es:(%rdi),%eax
  3e:	35                   	.byte 0x35
  3f:	2f                   	(bad)

final repro crashed as (corrupted=false):
kAFS: bad VL server IP address
BUG: unable to handle page fault for address: fffffffffffffffa
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD e186067 P4D e186067 PUD e188067 PMD 0 
Oops: Oops: 0002 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 5834 Comm: syz-executor362 Not tainted 6.15.0-rc1-syzkaller-00025-gbec7dcbc242c #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:arch_atomic_fetch_add arch/x86/include/asm/atomic.h:93 [inline]
RIP: 0010:raw_atomic_fetch_sub_release include/linux/atomic/atomic-arch-fallback.h:949 [inline]
RIP: 0010:atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:401 [inline]
RIP: 0010:__refcount_sub_and_test include/linux/refcount.h:389 [inline]
RIP: 0010:__refcount_dec_and_test include/linux/refcount.h:432 [inline]
RIP: 0010:refcount_dec_and_test include/linux/refcount.h:450 [inline]
RIP: 0010:afs_put_vlserverlist+0x3a/0x220 fs/afs/vl_list.c:67
Code: 53 48 83 ec 18 e8 e6 35 2f fe 48 85 ed 74 43 e8 dc 35 2f fe 4c 8d 65 10 be 04 00 00 00 bb ff ff ff ff 4c 89 e7 e8 76 ad 93 fe <f0> 0f c1 5d 10 31 ff 89 de e8 f8 30 2f fe 85 db 7e 29 e8 af 35 2f
RSP: 0018:ffffc90003e5fae0 EFLAGS: 00010246
RAX: 0000000000000001 RBX: 00000000ffffffff RCX: ffffffff838c071a
RDX: fffffc0000000000 RSI: 0000000000000004 RDI: fffffffffffffffa
RBP: ffffffffffffffea R08: 0000000000000001 R09: fffffbffffffffff
R10: fffffffffffffffd R11: 0000000000000001 R12: fffffffffffffffa
R13: ffffffffffffffea R14: ffff8880216ad700 R15: ffff888034ec2000
FS:  0000555561d3e380(0000) GS:ffff888124ab9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffa CR3: 000000007a922000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 afs_alloc_cell fs/afs/cell.c:218 [inline]
 afs_lookup_cell+0x12a5/0x1680 fs/afs/cell.c:264
 afs_cell_init+0x17a/0x380 fs/afs/cell.c:386
 afs_proc_rootcell_write+0x21f/0x290 fs/afs/proc.c:247
 proc_simple_write+0x114/0x1b0 fs/proc/generic.c:825
 pde_write fs/proc/inode.c:330 [inline]
 proc_reg_write+0x23d/0x330 fs/proc/inode.c:342
 vfs_write+0x25c/0x1180 fs/read_write.c:682
 ksys_write+0x12a/0x240 fs/read_write.c:736
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fab4ed8ba79
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 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:00007fff0c666448 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000200000000000 RCX: 00007fab4ed8ba79
RDX: 000000000000009e RSI: 0000200000000200 RDI: 0000000000000003
RBP: 00007fab4edfe5f0 R08: 0000000000000006 R09: 0000000000000006
R10: 0000000000000006 R11: 0000000000000246 R12: 0000000000000001
R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001
 </TASK>
Modules linked in:
CR2: fffffffffffffffa
---[ end trace 0000000000000000 ]---
RIP: 0010:arch_atomic_fetch_add arch/x86/include/asm/atomic.h:93 [inline]
RIP: 0010:raw_atomic_fetch_sub_release include/linux/atomic/atomic-arch-fallback.h:949 [inline]
RIP: 0010:atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:401 [inline]
RIP: 0010:__refcount_sub_and_test include/linux/refcount.h:389 [inline]
RIP: 0010:__refcount_dec_and_test include/linux/refcount.h:432 [inline]
RIP: 0010:refcount_dec_and_test include/linux/refcount.h:450 [inline]
RIP: 0010:afs_put_vlserverlist+0x3a/0x220 fs/afs/vl_list.c:67
Code: 53 48 83 ec 18 e8 e6 35 2f fe 48 85 ed 74 43 e8 dc 35 2f fe 4c 8d 65 10 be 04 00 00 00 bb ff ff ff ff 4c 89 e7 e8 76 ad 93 fe <f0> 0f c1 5d 10 31 ff 89 de e8 f8 30 2f fe 85 db 7e 29 e8 af 35 2f
RSP: 0018:ffffc90003e5fae0 EFLAGS: 00010246
RAX: 0000000000000001 RBX: 00000000ffffffff RCX: ffffffff838c071a
RDX: fffffc0000000000 RSI: 0000000000000004 RDI: fffffffffffffffa
RBP: ffffffffffffffea R08: 0000000000000001 R09: fffffbffffffffff
R10: fffffffffffffffd R11: 0000000000000001 R12: fffffffffffffffa
R13: ffffffffffffffea R14: ffff8880216ad700 R15: ffff888034ec2000
FS:  0000555561d3e380(0000) GS:ffff888124ab9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffa CR3: 000000007a922000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	53                   	push   %rbx
   1:	48 83 ec 18          	sub    $0x18,%rsp
   5:	e8 e6 35 2f fe       	call   0xfe2f35f0
   a:	48 85 ed             	test   %rbp,%rbp
   d:	74 43                	je     0x52
   f:	e8 dc 35 2f fe       	call   0xfe2f35f0
  14:	4c 8d 65 10          	lea    0x10(%rbp),%r12
  18:	be 04 00 00 00       	mov    $0x4,%esi
  1d:	bb ff ff ff ff       	mov    $0xffffffff,%ebx
  22:	4c 89 e7             	mov    %r12,%rdi
  25:	e8 76 ad 93 fe       	call   0xfe93ada0
* 2a:	f0 0f c1 5d 10       	lock xadd %ebx,0x10(%rbp) <-- trapping instruction
  2f:	31 ff                	xor    %edi,%edi
  31:	89 de                	mov    %ebx,%esi
  33:	e8 f8 30 2f fe       	call   0xfe2f3130
  38:	85 db                	test   %ebx,%ebx
  3a:	7e 29                	jle    0x65
  3c:	e8                   	.byte 0xe8
  3d:	af                   	scas   %es:(%rdi),%eax
  3e:	35                   	.byte 0x35
  3f:	2f                   	(bad)