Re: [PATCH] tracing: fix UAF caused by memory ordering issue
Mark Rutland 于2023年11月14日周二 06:17写道：
>
Hi, Mark and Steven
Thank you so much for the detailed comments.
> On Sun, Nov 12, 2023 at 11:00:30PM +0800, Kairui Song wrote:
> > From: Kairui Song
> >
> > Following kernel panic was observed when doing ftrace stress test:
>
> Can you share some more details:
>
> * What test specifically are you running? Can you share this so that others
> can
> try to reproduce the issue?
Yes, the panic happened when doing LTP ftrace stress test:
https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/tracing/ftrace_test/ftrace_stress_test.sh
>
> * Which machines are you testing on (i.e. which CPU microarchitecture is this
> seen with) ?
The panic was seen on a ARM64 VM, lscpu output:
Architecture: aarch64
CPU op-mode(s): 64-bit
Byte Order: Little Endian
CPU(s): 4
On-line CPU(s) list: 0-3
Vendor ID: HiSilicon
BIOS Vendor ID: QEMU
Model name: Kunpeng-920
BIOS Model name:virt-rhel8.6.0 CPU @ 2.0GHz
BIOS CPU family:1
Model: 0
Thread(s) per core: 1
Core(s) per socket: 1
Socket(s): 4
Stepping: 0x1
BogoMIPS: 200.00
Flags: fp asimd evtstrm aes pmull sha1 sha2 crc32
atomics fphp asimdhp cpuid asimdrdm jscvt fcma dcpop asimddp asimdfhm
The host machine is a Kunpeng-920 with 4 NUMA nodes and 128 cores.
>
> * Which compiler are you using?
gcc 12.3.1
>
> * The log shows this is with v6.1.61+. Can you reproduce this with a mainline
> kernel? e.g. v6.6 or v6.7-rc1?
It's reproducible with LTS, not tested with mainline, I'll try to
reproduce this with the latest mainline. But due to the low
reproducibility this may take a while.
>
> > Unable to handle kernel paging request at virtual address 9699b0f8ece28240
> > Mem abort info:
> > ESR = 0x9604
> > 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 = 0x0004
> > CM = 0, WnR = 0
> > [9699b0f8ece28240] address between user and kernel address ranges
> > Internal error: Oops: 9604 [#1] SMP
> > Modules linked in: rpcrdma rdma_cm iw_cm ib_cm ib_core rfkill vfat fat loop
> > fuse nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables ext4 mbcache
> > jbd2 sr_mod cdrom crct10dif_ce ghash_ce sha2_ce virtio_gpu virtio_dma_buf
> > drm_shmem_helper virtio_blk drm_kms_helper syscopyarea sysfillrect
> > sysimgblt fb_sys_fops virtio_console sha256_arm64 sha1_ce drm virtio_scsi
> > i2c_core virtio_net net_failover failover virtio_mmio dm_multipath dm_mod
> > autofs4 [last unloaded: ipmi_msghandler]
> > CPU: 0 PID: 499719 Comm: sh Kdump: loaded Not tainted 6.1.61+ #2
> > Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
> > pstate: 6045 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> > pc : __kmem_cache_alloc_node+0x1dc/0x2e4
> > lr : __kmem_cache_alloc_node+0xac/0x2e4
> > sp : 8ad23aa0
> > x29: 8ad23ab0 x28: 0004052b8000 x27: c513863b
> > x26: 0040 x25: c51384f21ca4 x24:
> > x23: d615521430b1b1a5 x22: c51386044770 x21:
> > x20: 0cc0 x19: c0001200 x18:
> > x17: x16: x15: e65e1630
> > x14: 0004 x13: c513863e67a0 x12: c513863af6d8
> > x11: 0001 x10: 8ad23aa0 x9 : c51385058078
> > x8 : 0018 x7 : 0001 x6 : 0010
> > x5 : c09c2280 x4 : c51384f21ca4 x3 : 0040
> > x2 : 9699b0f8ece28240 x1 : c09c2280 x0 : 9699b0f8ece28200
> > Call trace:
> > __kmem_cache_alloc_node+0x1dc/0x2e4
> > __kmalloc+0x6c/0x1c0
> > func_add+0x1a4/0x200
> > tracepoint_add_func+0x70/0x230
> > tracepoint_probe_register+0x6c/0xb4
> > trace_event_reg+0x8c/0xa0
> > __ftrace_event_enable_disable+0x17c/0x440
> > __ftrace_set_clr_event_nolock+0xe0/0x150
> > system_enable_write+0xe0/0x114
> > vfs_write+0xd0/0x2dc
> > ksys_write+0x78/0x110
> > __arm64_sys_write+0x24/0x30
> > invoke_syscall.constprop.0+0x58/0xf0
> > el0_svc_common.constprop.0+0x54/0x160
> > do_el0_svc+0x2c/0x60
> > el0_svc+0x40/0x1ac
> > el0t_64_sync_handler+0xf4/0x120
> > el0t_64_sync+0x19c/0x1a0
> > Code: b9402a63 f9405e77 8b030002 d5384101 (f8636803)
> >
> > Panic was caused by corrupted freelist pointer. After more debugging,
> > I found the root cause is UAF of slab allocated object in ftrace
> > introduced by commit eecb91b9f98d ("tracing: Fix memleak due to race
> > between current_tracer and trace"), and so far it's only reproducible
> > on some ARM64 machines, the UAF and free stack is:
> >
> > UAF:
> > kasan_report+0xa8/0x1bc
> > __asan_report_load8_noabort+0x28/0x3c
> > print_graph_function_flags+0x524/0x5a0
> > print_graph_function_event+0x28/0x40
> >
Re: [PATCH] tracing: fix UAF caused by memory ordering issue
On Sun, Nov 12, 2023 at 11:00:30PM +0800, Kairui Song wrote:
> From: Kairui Song
>
> Following kernel panic was observed when doing ftrace stress test:
Can you share some more details:
* What test specifically are you running? Can you share this so that others can
try to reproduce the issue?
* Which machines are you testing on (i.e. which CPU microarchitecture is this
seen with) ?
* Which compiler are you using?
* The log shows this is with v6.1.61+. Can you reproduce this with a mainline
kernel? e.g. v6.6 or v6.7-rc1?
> Unable to handle kernel paging request at virtual address 9699b0f8ece28240
> Mem abort info:
> ESR = 0x9604
> 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 = 0x0004
> CM = 0, WnR = 0
> [9699b0f8ece28240] address between user and kernel address ranges
> Internal error: Oops: 9604 [#1] SMP
> Modules linked in: rpcrdma rdma_cm iw_cm ib_cm ib_core rfkill vfat fat loop
> fuse nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables ext4 mbcache jbd2
> sr_mod cdrom crct10dif_ce ghash_ce sha2_ce virtio_gpu virtio_dma_buf
> drm_shmem_helper virtio_blk drm_kms_helper syscopyarea sysfillrect sysimgblt
> fb_sys_fops virtio_console sha256_arm64 sha1_ce drm virtio_scsi i2c_core
> virtio_net net_failover failover virtio_mmio dm_multipath dm_mod autofs4
> [last unloaded: ipmi_msghandler]
> CPU: 0 PID: 499719 Comm: sh Kdump: loaded Not tainted 6.1.61+ #2
> Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
> pstate: 6045 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : __kmem_cache_alloc_node+0x1dc/0x2e4
> lr : __kmem_cache_alloc_node+0xac/0x2e4
> sp : 8ad23aa0
> x29: 8ad23ab0 x28: 0004052b8000 x27: c513863b
> x26: 0040 x25: c51384f21ca4 x24:
> x23: d615521430b1b1a5 x22: c51386044770 x21:
> x20: 0cc0 x19: c0001200 x18:
> x17: x16: x15: e65e1630
> x14: 0004 x13: c513863e67a0 x12: c513863af6d8
> x11: 0001 x10: 8ad23aa0 x9 : c51385058078
> x8 : 0018 x7 : 0001 x6 : 0010
> x5 : c09c2280 x4 : c51384f21ca4 x3 : 0040
> x2 : 9699b0f8ece28240 x1 : c09c2280 x0 : 9699b0f8ece28200
> Call trace:
> __kmem_cache_alloc_node+0x1dc/0x2e4
> __kmalloc+0x6c/0x1c0
> func_add+0x1a4/0x200
> tracepoint_add_func+0x70/0x230
> tracepoint_probe_register+0x6c/0xb4
> trace_event_reg+0x8c/0xa0
> __ftrace_event_enable_disable+0x17c/0x440
> __ftrace_set_clr_event_nolock+0xe0/0x150
> system_enable_write+0xe0/0x114
> vfs_write+0xd0/0x2dc
> ksys_write+0x78/0x110
> __arm64_sys_write+0x24/0x30
> invoke_syscall.constprop.0+0x58/0xf0
> el0_svc_common.constprop.0+0x54/0x160
> do_el0_svc+0x2c/0x60
> el0_svc+0x40/0x1ac
> el0t_64_sync_handler+0xf4/0x120
> el0t_64_sync+0x19c/0x1a0
> Code: b9402a63 f9405e77 8b030002 d5384101 (f8636803)
>
> Panic was caused by corrupted freelist pointer. After more debugging,
> I found the root cause is UAF of slab allocated object in ftrace
> introduced by commit eecb91b9f98d ("tracing: Fix memleak due to race
> between current_tracer and trace"), and so far it's only reproducible
> on some ARM64 machines, the UAF and free stack is:
>
> UAF:
> kasan_report+0xa8/0x1bc
> __asan_report_load8_noabort+0x28/0x3c
> print_graph_function_flags+0x524/0x5a0
> print_graph_function_event+0x28/0x40
> print_trace_line+0x5c4/0x1030
> s_show+0xf0/0x460
> seq_read_iter+0x930/0xf5c
> seq_read+0x130/0x1d0
> vfs_read+0x288/0x840
> ksys_read+0x130/0x270
> __arm64_sys_read+0x78/0xac
> invoke_syscall.constprop.0+0x90/0x224
> do_el0_svc+0x118/0x3dc
> el0_svc+0x54/0x120
> el0t_64_sync_handler+0xf4/0x120
> el0t_64_sync+0x19c/0x1a0
>
> Freed by:
> kasan_save_free_info+0x38/0x5c
> __kasan_slab_free+0xe8/0x154
> slab_free_freelist_hook+0xfc/0x1e0
> __kmem_cache_free+0x138/0x260
> kfree+0xd0/0x1d0
> graph_trace_close+0x60/0x90
> s_start+0x610/0x910
> seq_read_iter+0x274/0xf5c
> seq_read+0x130/0x1d0
> vfs_read+0x288/0x840
> ksys_read+0x130/0x270
> __arm64_sys_read+0x78/0xac
> invoke_syscall.constprop.0+0x90/0x224
> do_el0_svc+0x118/0x3dc
> el0_svc+0x54/0x120
> el0t_64_sync_handler+0xf4/0x120
> el0t_64_sync+0x19c/0x1a0
>
> Despite the s_start and s_show being serialized by seq_file mutex,
> the tracer struct copy in s_start introduced by the commit mentioned
> above is not atomic nor guarenteened to be seen by all CPUs. So
> following seneriao is possible (and actually happened):
>
> CPU 1 CPU 2
> seq_read_iter seq_read_iter
> mutex_lock(>lock);
> s_start
> // iter->trace is graph_trace
> iter->trace->close(iter);
> graph_trace_close
> kfree(data) <- *** data released here ***
> //
Re: [PATCH] tracing: fix UAF caused by memory ordering issue
On Sun, 12 Nov 2023 23:00:30 +0800
Kairui Song wrote:
> From: Kairui Song
>
> Following kernel panic was observed when doing ftrace stress test:
>
> Unable to handle kernel paging request at virtual address 9699b0f8ece28240
> Mem abort info:
> ESR = 0x9604
> 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 = 0x0004
> CM = 0, WnR = 0
> [9699b0f8ece28240] address between user and kernel address ranges
> Internal error: Oops: 9604 [#1] SMP
> Modules linked in: rpcrdma rdma_cm iw_cm ib_cm ib_core rfkill vfat fat loop
> fuse nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables ext4 mbcache jbd2
> sr_mod cdrom crct10dif_ce ghash_ce sha2_ce virtio_gpu virtio_dma_buf
> drm_shmem_helper virtio_blk drm_kms_helper syscopyarea sysfillrect sysimgblt
> fb_sys_fops virtio_console sha256_arm64 sha1_ce drm virtio_scsi i2c_core
> virtio_net net_failover failover virtio_mmio dm_multipath dm_mod autofs4
> [last unloaded: ipmi_msghandler]
> CPU: 0 PID: 499719 Comm: sh Kdump: loaded Not tainted 6.1.61+ #2
> Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
> pstate: 6045 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : __kmem_cache_alloc_node+0x1dc/0x2e4
> lr : __kmem_cache_alloc_node+0xac/0x2e4
> sp : 8ad23aa0
> x29: 8ad23ab0 x28: 0004052b8000 x27: c513863b
> x26: 0040 x25: c51384f21ca4 x24:
> x23: d615521430b1b1a5 x22: c51386044770 x21:
> x20: 0cc0 x19: c0001200 x18:
> x17: x16: x15: e65e1630
> x14: 0004 x13: c513863e67a0 x12: c513863af6d8
> x11: 0001 x10: 8ad23aa0 x9 : c51385058078
> x8 : 0018 x7 : 0001 x6 : 0010
> x5 : c09c2280 x4 : c51384f21ca4 x3 : 0040
> x2 : 9699b0f8ece28240 x1 : c09c2280 x0 : 9699b0f8ece28200
> Call trace:
> __kmem_cache_alloc_node+0x1dc/0x2e4
> __kmalloc+0x6c/0x1c0
> func_add+0x1a4/0x200
> tracepoint_add_func+0x70/0x230
> tracepoint_probe_register+0x6c/0xb4
> trace_event_reg+0x8c/0xa0
> __ftrace_event_enable_disable+0x17c/0x440
> __ftrace_set_clr_event_nolock+0xe0/0x150
> system_enable_write+0xe0/0x114
> vfs_write+0xd0/0x2dc
> ksys_write+0x78/0x110
> __arm64_sys_write+0x24/0x30
> invoke_syscall.constprop.0+0x58/0xf0
> el0_svc_common.constprop.0+0x54/0x160
> do_el0_svc+0x2c/0x60
> el0_svc+0x40/0x1ac
> el0t_64_sync_handler+0xf4/0x120
> el0t_64_sync+0x19c/0x1a0
> Code: b9402a63 f9405e77 8b030002 d5384101 (f8636803)
>
> Panic was caused by corrupted freelist pointer. After more debugging,
So you are saying that the above is caused by the free list corruption
(hence we can ignore the stack trace)
> I found the root cause is UAF of slab allocated object in ftrace
> introduced by commit eecb91b9f98d ("tracing: Fix memleak due to race
> between current_tracer and trace"), and so far it's only reproducible
> on some ARM64 machines, the UAF and free stack is:
>
> UAF:
> kasan_report+0xa8/0x1bc
> __asan_report_load8_noabort+0x28/0x3c
> print_graph_function_flags+0x524/0x5a0
> print_graph_function_event+0x28/0x40
> print_trace_line+0x5c4/0x1030
> s_show+0xf0/0x460
> seq_read_iter+0x930/0xf5c
> seq_read+0x130/0x1d0
> vfs_read+0x288/0x840
> ksys_read+0x130/0x270
> __arm64_sys_read+0x78/0xac
> invoke_syscall.constprop.0+0x90/0x224
> do_el0_svc+0x118/0x3dc
> el0_svc+0x54/0x120
> el0t_64_sync_handler+0xf4/0x120
> el0t_64_sync+0x19c/0x1a0
>
> Freed by:
> kasan_save_free_info+0x38/0x5c
> __kasan_slab_free+0xe8/0x154
> slab_free_freelist_hook+0xfc/0x1e0
> __kmem_cache_free+0x138/0x260
> kfree+0xd0/0x1d0
> graph_trace_close+0x60/0x90
> s_start+0x610/0x910
> seq_read_iter+0x274/0xf5c
> seq_read+0x130/0x1d0
> vfs_read+0x288/0x840
> ksys_read+0x130/0x270
> __arm64_sys_read+0x78/0xac
> invoke_syscall.constprop.0+0x90/0x224
> do_el0_svc+0x118/0x3dc
> el0_svc+0x54/0x120
> el0t_64_sync_handler+0xf4/0x120
> el0t_64_sync+0x19c/0x1a0
>
> Despite the s_start and s_show being serialized by seq_file mutex,
> the tracer struct copy in s_start introduced by the commit mentioned
> above is not atomic nor guarenteened to be seen by all CPUs. So
> following seneriao is possible (and actually happened):
What do you mean it is not atomic? The change should be done under a
trace_types_lock, right? Doing something under a mutex is suppose to
protect it.
>
> CPU 1 CPU 2
> seq_read_iter seq_read_iter
> mutex_lock(>lock);
> s_start
> // iter->trace is graph_trace
> iter->trace->close(iter);
> graph_trace_close
> kfree(data) <- *** data released here ***
> // copy current_trace to iter->trace
> // but not synced to CPU 2
> *iter->trace = *tr->current_trace
> ... (goes on)
>
[PATCH] tracing: fix UAF caused by memory ordering issue
From: Kairui Song
Following kernel panic was observed when doing ftrace stress test:
Unable to handle kernel paging request at virtual address 9699b0f8ece28240
Mem abort info:
ESR = 0x9604
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 = 0x0004
CM = 0, WnR = 0
[9699b0f8ece28240] address between user and kernel address ranges
Internal error: Oops: 9604 [#1] SMP
Modules linked in: rpcrdma rdma_cm iw_cm ib_cm ib_core rfkill vfat fat loop
fuse nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables ext4 mbcache jbd2
sr_mod cdrom crct10dif_ce ghash_ce sha2_ce virtio_gpu virtio_dma_buf
drm_shmem_helper virtio_blk drm_kms_helper syscopyarea sysfillrect sysimgblt
fb_sys_fops virtio_console sha256_arm64 sha1_ce drm virtio_scsi i2c_core
virtio_net net_failover failover virtio_mmio dm_multipath dm_mod autofs4 [last
unloaded: ipmi_msghandler]
CPU: 0 PID: 499719 Comm: sh Kdump: loaded Not tainted 6.1.61+ #2
Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
pstate: 6045 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __kmem_cache_alloc_node+0x1dc/0x2e4
lr : __kmem_cache_alloc_node+0xac/0x2e4
sp : 8ad23aa0
x29: 8ad23ab0 x28: 0004052b8000 x27: c513863b
x26: 0040 x25: c51384f21ca4 x24:
x23: d615521430b1b1a5 x22: c51386044770 x21:
x20: 0cc0 x19: c0001200 x18:
x17: x16: x15: e65e1630
x14: 0004 x13: c513863e67a0 x12: c513863af6d8
x11: 0001 x10: 8ad23aa0 x9 : c51385058078
x8 : 0018 x7 : 0001 x6 : 0010
x5 : c09c2280 x4 : c51384f21ca4 x3 : 0040
x2 : 9699b0f8ece28240 x1 : c09c2280 x0 : 9699b0f8ece28200
Call trace:
__kmem_cache_alloc_node+0x1dc/0x2e4
__kmalloc+0x6c/0x1c0
func_add+0x1a4/0x200
tracepoint_add_func+0x70/0x230
tracepoint_probe_register+0x6c/0xb4
trace_event_reg+0x8c/0xa0
__ftrace_event_enable_disable+0x17c/0x440
__ftrace_set_clr_event_nolock+0xe0/0x150
system_enable_write+0xe0/0x114
vfs_write+0xd0/0x2dc
ksys_write+0x78/0x110
__arm64_sys_write+0x24/0x30
invoke_syscall.constprop.0+0x58/0xf0
el0_svc_common.constprop.0+0x54/0x160
do_el0_svc+0x2c/0x60
el0_svc+0x40/0x1ac
el0t_64_sync_handler+0xf4/0x120
el0t_64_sync+0x19c/0x1a0
Code: b9402a63 f9405e77 8b030002 d5384101 (f8636803)
Panic was caused by corrupted freelist pointer. After more debugging,
I found the root cause is UAF of slab allocated object in ftrace
introduced by commit eecb91b9f98d ("tracing: Fix memleak due to race
between current_tracer and trace"), and so far it's only reproducible
on some ARM64 machines, the UAF and free stack is:
UAF:
kasan_report+0xa8/0x1bc
__asan_report_load8_noabort+0x28/0x3c
print_graph_function_flags+0x524/0x5a0
print_graph_function_event+0x28/0x40
print_trace_line+0x5c4/0x1030
s_show+0xf0/0x460
seq_read_iter+0x930/0xf5c
seq_read+0x130/0x1d0
vfs_read+0x288/0x840
ksys_read+0x130/0x270
__arm64_sys_read+0x78/0xac
invoke_syscall.constprop.0+0x90/0x224
do_el0_svc+0x118/0x3dc
el0_svc+0x54/0x120
el0t_64_sync_handler+0xf4/0x120
el0t_64_sync+0x19c/0x1a0
Freed by:
kasan_save_free_info+0x38/0x5c
__kasan_slab_free+0xe8/0x154
slab_free_freelist_hook+0xfc/0x1e0
__kmem_cache_free+0x138/0x260
kfree+0xd0/0x1d0
graph_trace_close+0x60/0x90
s_start+0x610/0x910
seq_read_iter+0x274/0xf5c
seq_read+0x130/0x1d0
vfs_read+0x288/0x840
ksys_read+0x130/0x270
__arm64_sys_read+0x78/0xac
invoke_syscall.constprop.0+0x90/0x224
do_el0_svc+0x118/0x3dc
el0_svc+0x54/0x120
el0t_64_sync_handler+0xf4/0x120
el0t_64_sync+0x19c/0x1a0
Despite the s_start and s_show being serialized by seq_file mutex,
the tracer struct copy in s_start introduced by the commit mentioned
above is not atomic nor guarenteened to be seen by all CPUs. So
following seneriao is possible (and actually happened):
CPU 1 CPU 2
seq_read_iter seq_read_iter
mutex_lock(>lock);
s_start
// iter->trace is graph_trace
iter->trace->close(iter);
graph_trace_close
kfree(data) <- *** data released here ***
// copy current_trace to iter->trace
// but not synced to CPU 2
*iter->trace = *tr->current_trace
... (goes on)
mutex_unlock(>lock);
mutex_lock(>lock);
... (s_start and other work)
s_show
print_trace_line(iter)
// iter->trace is still
// old value (graph_trace)
iter->trace->print_line()
print_graph_function_flags
