| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
cachefiles: fix slab-use-after-free in fscache_withdraw_volume()
We got the following issue in our fault injection stress test:
==================================================================
BUG: KASAN: slab-use-after-free in fscache_withdraw_volume+0x2e1/0x370
Read of size 4 at addr ffff88810680be08 by task ondemand-04-dae/5798
CPU: 0 PID: 5798 Comm: ondemand-04-dae Not tainted 6.8.0-dirty #565
Call Trace:
kasan_check_range+0xf6/0x1b0
fscache_withdraw_volume+0x2e1/0x370
cachefiles_withdraw_volume+0x31/0x50
cachefiles_withdraw_cache+0x3ad/0x900
cachefiles_put_unbind_pincount+0x1f6/0x250
cachefiles_daemon_release+0x13b/0x290
__fput+0x204/0xa00
task_work_run+0x139/0x230
Allocated by task 5820:
__kmalloc+0x1df/0x4b0
fscache_alloc_volume+0x70/0x600
__fscache_acquire_volume+0x1c/0x610
erofs_fscache_register_volume+0x96/0x1a0
erofs_fscache_register_fs+0x49a/0x690
erofs_fc_fill_super+0x6c0/0xcc0
vfs_get_super+0xa9/0x140
vfs_get_tree+0x8e/0x300
do_new_mount+0x28c/0x580
[...]
Freed by task 5820:
kfree+0xf1/0x2c0
fscache_put_volume.part.0+0x5cb/0x9e0
erofs_fscache_unregister_fs+0x157/0x1b0
erofs_kill_sb+0xd9/0x1c0
deactivate_locked_super+0xa3/0x100
vfs_get_super+0x105/0x140
vfs_get_tree+0x8e/0x300
do_new_mount+0x28c/0x580
[...]
==================================================================
Following is the process that triggers the issue:
mount failed | daemon exit
------------------------------------------------------------
deactivate_locked_super cachefiles_daemon_release
erofs_kill_sb
erofs_fscache_unregister_fs
fscache_relinquish_volume
__fscache_relinquish_volume
fscache_put_volume(fscache_volume, fscache_volume_put_relinquish)
zero = __refcount_dec_and_test(&fscache_volume->ref, &ref);
cachefiles_put_unbind_pincount
cachefiles_daemon_unbind
cachefiles_withdraw_cache
cachefiles_withdraw_volumes
list_del_init(&volume->cache_link)
fscache_free_volume(fscache_volume)
cache->ops->free_volume
cachefiles_free_volume
list_del_init(&cachefiles_volume->cache_link);
kfree(fscache_volume)
cachefiles_withdraw_volume
fscache_withdraw_volume
fscache_volume->n_accesses
// fscache_volume UAF !!!
The fscache_volume in cache->volumes must not have been freed yet, but its
reference count may be 0. So use the new fscache_try_get_volume() helper
function try to get its reference count.
If the reference count of fscache_volume is 0, fscache_put_volume() is
freeing it, so wait for it to be removed from cache->volumes.
If its reference count is not 0, call cachefiles_withdraw_volume() with
reference count protection to avoid the above issue. |
| In the Linux kernel, the following vulnerability has been resolved:
cachefiles: fix slab-use-after-free in cachefiles_withdraw_cookie()
We got the following issue in our fault injection stress test:
==================================================================
BUG: KASAN: slab-use-after-free in cachefiles_withdraw_cookie+0x4d9/0x600
Read of size 8 at addr ffff888118efc000 by task kworker/u78:0/109
CPU: 13 PID: 109 Comm: kworker/u78:0 Not tainted 6.8.0-dirty #566
Call Trace:
<TASK>
kasan_report+0x93/0xc0
cachefiles_withdraw_cookie+0x4d9/0x600
fscache_cookie_state_machine+0x5c8/0x1230
fscache_cookie_worker+0x91/0x1c0
process_one_work+0x7fa/0x1800
[...]
Allocated by task 117:
kmalloc_trace+0x1b3/0x3c0
cachefiles_acquire_volume+0xf3/0x9c0
fscache_create_volume_work+0x97/0x150
process_one_work+0x7fa/0x1800
[...]
Freed by task 120301:
kfree+0xf1/0x2c0
cachefiles_withdraw_cache+0x3fa/0x920
cachefiles_put_unbind_pincount+0x1f6/0x250
cachefiles_daemon_release+0x13b/0x290
__fput+0x204/0xa00
task_work_run+0x139/0x230
do_exit+0x87a/0x29b0
[...]
==================================================================
Following is the process that triggers the issue:
p1 | p2
------------------------------------------------------------
fscache_begin_lookup
fscache_begin_volume_access
fscache_cache_is_live(fscache_cache)
cachefiles_daemon_release
cachefiles_put_unbind_pincount
cachefiles_daemon_unbind
cachefiles_withdraw_cache
fscache_withdraw_cache
fscache_set_cache_state(cache, FSCACHE_CACHE_IS_WITHDRAWN);
cachefiles_withdraw_objects(cache)
fscache_wait_for_objects(fscache)
atomic_read(&fscache_cache->object_count) == 0
fscache_perform_lookup
cachefiles_lookup_cookie
cachefiles_alloc_object
refcount_set(&object->ref, 1);
object->volume = volume
fscache_count_object(vcookie->cache);
atomic_inc(&fscache_cache->object_count)
cachefiles_withdraw_volumes
cachefiles_withdraw_volume
fscache_withdraw_volume
__cachefiles_free_volume
kfree(cachefiles_volume)
fscache_cookie_state_machine
cachefiles_withdraw_cookie
cache = object->volume->cache;
// cachefiles_volume UAF !!!
After setting FSCACHE_CACHE_IS_WITHDRAWN, wait for all the cookie lookups
to complete first, and then wait for fscache_cache->object_count == 0 to
avoid the cookie exiting after the volume has been freed and triggering
the above issue. Therefore call fscache_withdraw_volume() before calling
cachefiles_withdraw_objects().
This way, after setting FSCACHE_CACHE_IS_WITHDRAWN, only the following two
cases will occur:
1) fscache_begin_lookup fails in fscache_begin_volume_access().
2) fscache_withdraw_volume() will ensure that fscache_count_object() has
been executed before calling fscache_wait_for_objects(). |
| In the Linux kernel, the following vulnerability has been resolved:
cachefiles: wait for ondemand_object_worker to finish when dropping object
When queuing ondemand_object_worker() to re-open the object,
cachefiles_object is not pinned. The cachefiles_object may be freed when
the pending read request is completed intentionally and the related
erofs is umounted. If ondemand_object_worker() runs after the object is
freed, it will incur use-after-free problem as shown below.
process A processs B process C process D
cachefiles_ondemand_send_req()
// send a read req X
// wait for its completion
// close ondemand fd
cachefiles_ondemand_fd_release()
// set object as CLOSE
cachefiles_ondemand_daemon_read()
// set object as REOPENING
queue_work(fscache_wq, &info->ondemand_work)
// close /dev/cachefiles
cachefiles_daemon_release
cachefiles_flush_reqs
complete(&req->done)
// read req X is completed
// umount the erofs fs
cachefiles_put_object()
// object will be freed
cachefiles_ondemand_deinit_obj_info()
kmem_cache_free(object)
// both info and object are freed
ondemand_object_worker()
When dropping an object, it is no longer necessary to reopen the object,
so use cancel_work_sync() to cancel or wait for ondemand_object_worker()
to finish. |
| In the Linux kernel, the following vulnerability has been resolved:
cachefiles: cyclic allocation of msg_id to avoid reuse
Reusing the msg_id after a maliciously completed reopen request may cause
a read request to remain unprocessed and result in a hung, as shown below:
t1 | t2 | t3
-------------------------------------------------
cachefiles_ondemand_select_req
cachefiles_ondemand_object_is_close(A)
cachefiles_ondemand_set_object_reopening(A)
queue_work(fscache_object_wq, &info->work)
ondemand_object_worker
cachefiles_ondemand_init_object(A)
cachefiles_ondemand_send_req(OPEN)
// get msg_id 6
wait_for_completion(&req_A->done)
cachefiles_ondemand_daemon_read
// read msg_id 6 req_A
cachefiles_ondemand_get_fd
copy_to_user
// Malicious completion msg_id 6
copen 6,-1
cachefiles_ondemand_copen
complete(&req_A->done)
// will not set the object to close
// because ondemand_id && fd is valid.
// ondemand_object_worker() is done
// but the object is still reopening.
// new open req_B
cachefiles_ondemand_init_object(B)
cachefiles_ondemand_send_req(OPEN)
// reuse msg_id 6
process_open_req
copen 6,A.size
// The expected failed copen was executed successfully
Expect copen to fail, and when it does, it closes fd, which sets the
object to close, and then close triggers reopen again. However, due to
msg_id reuse resulting in a successful copen, the anonymous fd is not
closed until the daemon exits. Therefore read requests waiting for reopen
to complete may trigger hung task.
To avoid this issue, allocate the msg_id cyclically to avoid reusing the
msg_id for a very short duration of time. |
| In the Linux kernel, the following vulnerability has been resolved:
filelock: fix potential use-after-free in posix_lock_inode
Light Hsieh reported a KASAN UAF warning in trace_posix_lock_inode().
The request pointer had been changed earlier to point to a lock entry
that was added to the inode's list. However, before the tracepoint could
fire, another task raced in and freed that lock.
Fix this by moving the tracepoint inside the spinlock, which should
ensure that this doesn't happen. |
| In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_tables: prefer nft_chain_validate
nft_chain_validate already performs loop detection because a cycle will
result in a call stack overflow (ctx->level >= NFT_JUMP_STACK_SIZE).
It also follows maps via ->validate callback in nft_lookup, so there
appears no reason to iterate the maps again.
nf_tables_check_loops() and all its helper functions can be removed.
This improves ruleset load time significantly, from 23s down to 12s.
This also fixes a crash bug. Old loop detection code can result in
unbounded recursion:
BUG: TASK stack guard page was hit at ....
Oops: stack guard page: 0000 [#1] PREEMPT SMP KASAN
CPU: 4 PID: 1539 Comm: nft Not tainted 6.10.0-rc5+ #1
[..]
with a suitable ruleset during validation of register stores.
I can't see any actual reason to attempt to check for this from
nft_validate_register_store(), at this point the transaction is still in
progress, so we don't have a full picture of the rule graph.
For nf-next it might make sense to either remove it or make this depend
on table->validate_state in case we could catch an error earlier
(for improved error reporting to userspace). |
| In the Linux kernel, the following vulnerability has been resolved:
net/sched: Fix UAF when resolving a clash
KASAN reports the following UAF:
BUG: KASAN: slab-use-after-free in tcf_ct_flow_table_process_conn+0x12b/0x380 [act_ct]
Read of size 1 at addr ffff888c07603600 by task handler130/6469
Call Trace:
<IRQ>
dump_stack_lvl+0x48/0x70
print_address_description.constprop.0+0x33/0x3d0
print_report+0xc0/0x2b0
kasan_report+0xd0/0x120
__asan_load1+0x6c/0x80
tcf_ct_flow_table_process_conn+0x12b/0x380 [act_ct]
tcf_ct_act+0x886/0x1350 [act_ct]
tcf_action_exec+0xf8/0x1f0
fl_classify+0x355/0x360 [cls_flower]
__tcf_classify+0x1fd/0x330
tcf_classify+0x21c/0x3c0
sch_handle_ingress.constprop.0+0x2c5/0x500
__netif_receive_skb_core.constprop.0+0xb25/0x1510
__netif_receive_skb_list_core+0x220/0x4c0
netif_receive_skb_list_internal+0x446/0x620
napi_complete_done+0x157/0x3d0
gro_cell_poll+0xcf/0x100
__napi_poll+0x65/0x310
net_rx_action+0x30c/0x5c0
__do_softirq+0x14f/0x491
__irq_exit_rcu+0x82/0xc0
irq_exit_rcu+0xe/0x20
common_interrupt+0xa1/0xb0
</IRQ>
<TASK>
asm_common_interrupt+0x27/0x40
Allocated by task 6469:
kasan_save_stack+0x38/0x70
kasan_set_track+0x25/0x40
kasan_save_alloc_info+0x1e/0x40
__kasan_krealloc+0x133/0x190
krealloc+0xaa/0x130
nf_ct_ext_add+0xed/0x230 [nf_conntrack]
tcf_ct_act+0x1095/0x1350 [act_ct]
tcf_action_exec+0xf8/0x1f0
fl_classify+0x355/0x360 [cls_flower]
__tcf_classify+0x1fd/0x330
tcf_classify+0x21c/0x3c0
sch_handle_ingress.constprop.0+0x2c5/0x500
__netif_receive_skb_core.constprop.0+0xb25/0x1510
__netif_receive_skb_list_core+0x220/0x4c0
netif_receive_skb_list_internal+0x446/0x620
napi_complete_done+0x157/0x3d0
gro_cell_poll+0xcf/0x100
__napi_poll+0x65/0x310
net_rx_action+0x30c/0x5c0
__do_softirq+0x14f/0x491
Freed by task 6469:
kasan_save_stack+0x38/0x70
kasan_set_track+0x25/0x40
kasan_save_free_info+0x2b/0x60
____kasan_slab_free+0x180/0x1f0
__kasan_slab_free+0x12/0x30
slab_free_freelist_hook+0xd2/0x1a0
__kmem_cache_free+0x1a2/0x2f0
kfree+0x78/0x120
nf_conntrack_free+0x74/0x130 [nf_conntrack]
nf_ct_destroy+0xb2/0x140 [nf_conntrack]
__nf_ct_resolve_clash+0x529/0x5d0 [nf_conntrack]
nf_ct_resolve_clash+0xf6/0x490 [nf_conntrack]
__nf_conntrack_confirm+0x2c6/0x770 [nf_conntrack]
tcf_ct_act+0x12ad/0x1350 [act_ct]
tcf_action_exec+0xf8/0x1f0
fl_classify+0x355/0x360 [cls_flower]
__tcf_classify+0x1fd/0x330
tcf_classify+0x21c/0x3c0
sch_handle_ingress.constprop.0+0x2c5/0x500
__netif_receive_skb_core.constprop.0+0xb25/0x1510
__netif_receive_skb_list_core+0x220/0x4c0
netif_receive_skb_list_internal+0x446/0x620
napi_complete_done+0x157/0x3d0
gro_cell_poll+0xcf/0x100
__napi_poll+0x65/0x310
net_rx_action+0x30c/0x5c0
__do_softirq+0x14f/0x491
The ct may be dropped if a clash has been resolved but is still passed to
the tcf_ct_flow_table_process_conn function for further usage. This issue
can be fixed by retrieving ct from skb again after confirming conntrack. |
| In the Linux kernel, the following vulnerability has been resolved:
firmware: cs_dsp: Fix overflow checking of wmfw header
Fix the checking that firmware file buffer is large enough for the
wmfw header, to prevent overrunning the buffer.
The original code tested that the firmware data buffer contained
enough bytes for the sums of the size of the structs
wmfw_header + wmfw_adsp1_sizes + wmfw_footer
But wmfw_adsp1_sizes is only used on ADSP1 firmware. For ADSP2 and
Halo Core the equivalent struct is wmfw_adsp2_sizes, which is
4 bytes longer. So the length check didn't guarantee that there
are enough bytes in the firmware buffer for a header with
wmfw_adsp2_sizes.
This patch splits the length check into three separate parts. Each
of the wmfw_header, wmfw_adsp?_sizes and wmfw_footer are checked
separately before they are used. |
| In the Linux kernel, the following vulnerability has been resolved:
platform/x86: toshiba_acpi: Fix array out-of-bounds access
In order to use toshiba_dmi_quirks[] together with the standard DMI
matching functions, it must be terminated by a empty entry.
Since this entry is missing, an array out-of-bounds access occurs
every time the quirk list is processed.
Fix this by adding the terminating empty entry. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/amdkfd: don't allow mapping the MMIO HDP page with large pages
We don't get the right offset in that case. The GPU has
an unused 4K area of the register BAR space into which you can
remap registers. We remap the HDP flush registers into this
space to allow userspace (CPU or GPU) to flush the HDP when it
updates VRAM. However, on systems with >4K pages, we end up
exposing PAGE_SIZE of MMIO space. |
| In the Linux kernel, the following vulnerability has been resolved:
bpf: Avoid splat in pskb_pull_reason
syzkaller builds (CONFIG_DEBUG_NET=y) frequently trigger a debug
hint in pskb_may_pull.
We'd like to retain this debug check because it might hint at integer
overflows and other issues (kernel code should pull headers, not huge
value).
In bpf case, this splat isn't interesting at all: such (nonsensical)
bpf programs are typically generated by a fuzzer anyway.
Do what Eric suggested and suppress such warning.
For CONFIG_DEBUG_NET=n we don't need the extra check because
pskb_may_pull will do the right thing: return an error without the
WARN() backtrace. |
| In the Linux kernel, the following vulnerability has been resolved:
ptp: fix integer overflow in max_vclocks_store
On 32bit systems, the "4 * max" multiply can overflow. Use kcalloc()
to do the allocation to prevent this. |
| In the Linux kernel, the following vulnerability has been resolved:
KVM: arm64: Disassociate vcpus from redistributor region on teardown
When tearing down a redistributor region, make sure we don't have
any dangling pointer to that region stored in a vcpu. |
| In the Linux kernel, the following vulnerability has been resolved:
dmaengine: idxd: Fix possible Use-After-Free in irq_process_work_list
Use list_for_each_entry_safe() to allow iterating through the list and
deleting the entry in the iteration process. The descriptor is freed via
idxd_desc_complete() and there's a slight chance may cause issue for
the list iterator when the descriptor is reused by another thread
without it being deleted from the list. |
| In the Linux kernel, the following vulnerability has been resolved:
net: do not leave a dangling sk pointer, when socket creation fails
It is possible to trigger a use-after-free by:
* attaching an fentry probe to __sock_release() and the probe calling the
bpf_get_socket_cookie() helper
* running traceroute -I 1.1.1.1 on a freshly booted VM
A KASAN enabled kernel will log something like below (decoded and stripped):
==================================================================
BUG: KASAN: slab-use-after-free in __sock_gen_cookie (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-instrumented.h:1611 net/core/sock_diag.c:29)
Read of size 8 at addr ffff888007110dd8 by task traceroute/299
CPU: 2 PID: 299 Comm: traceroute Tainted: G E 6.10.0-rc2+ #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl (lib/dump_stack.c:117 (discriminator 1))
print_report (mm/kasan/report.c:378 mm/kasan/report.c:488)
? __sock_gen_cookie (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-instrumented.h:1611 net/core/sock_diag.c:29)
kasan_report (mm/kasan/report.c:603)
? __sock_gen_cookie (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-instrumented.h:1611 net/core/sock_diag.c:29)
kasan_check_range (mm/kasan/generic.c:183 mm/kasan/generic.c:189)
__sock_gen_cookie (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-instrumented.h:1611 net/core/sock_diag.c:29)
bpf_get_socket_ptr_cookie (./arch/x86/include/asm/preempt.h:94 ./include/linux/sock_diag.h:42 net/core/filter.c:5094 net/core/filter.c:5092)
bpf_prog_875642cf11f1d139___sock_release+0x6e/0x8e
bpf_trampoline_6442506592+0x47/0xaf
__sock_release (net/socket.c:652)
__sock_create (net/socket.c:1601)
...
Allocated by task 299 on cpu 2 at 78.328492s:
kasan_save_stack (mm/kasan/common.c:48)
kasan_save_track (mm/kasan/common.c:68)
__kasan_slab_alloc (mm/kasan/common.c:312 mm/kasan/common.c:338)
kmem_cache_alloc_noprof (mm/slub.c:3941 mm/slub.c:4000 mm/slub.c:4007)
sk_prot_alloc (net/core/sock.c:2075)
sk_alloc (net/core/sock.c:2134)
inet_create (net/ipv4/af_inet.c:327 net/ipv4/af_inet.c:252)
__sock_create (net/socket.c:1572)
__sys_socket (net/socket.c:1660 net/socket.c:1644 net/socket.c:1706)
__x64_sys_socket (net/socket.c:1718)
do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
Freed by task 299 on cpu 2 at 78.328502s:
kasan_save_stack (mm/kasan/common.c:48)
kasan_save_track (mm/kasan/common.c:68)
kasan_save_free_info (mm/kasan/generic.c:582)
poison_slab_object (mm/kasan/common.c:242)
__kasan_slab_free (mm/kasan/common.c:256)
kmem_cache_free (mm/slub.c:4437 mm/slub.c:4511)
__sk_destruct (net/core/sock.c:2117 net/core/sock.c:2208)
inet_create (net/ipv4/af_inet.c:397 net/ipv4/af_inet.c:252)
__sock_create (net/socket.c:1572)
__sys_socket (net/socket.c:1660 net/socket.c:1644 net/socket.c:1706)
__x64_sys_socket (net/socket.c:1718)
do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
Fix this by clearing the struct socket reference in sk_common_release() to cover
all protocol families create functions, which may already attached the
reference to the sk object with sock_init_data(). |
| In the Linux kernel, the following vulnerability has been resolved:
net/mlx5: Fix tainted pointer delete is case of flow rules creation fail
In case of flow rule creation fail in mlx5_lag_create_port_sel_table(),
instead of previously created rules, the tainted pointer is deleted
deveral times.
Fix this bug by using correct flow rules pointers.
Found by Linux Verification Center (linuxtesting.org) with SVACE. |
| In the Linux kernel, the following vulnerability has been resolved:
net: wwan: iosm: Fix tainted pointer delete is case of region creation fail
In case of region creation fail in ipc_devlink_create_region(), previously
created regions delete process starts from tainted pointer which actually
holds error code value.
Fix this bug by decreasing region index before delete.
Found by Linux Verification Center (linuxtesting.org) with SVACE. |
| In the Linux kernel, the following vulnerability has been resolved:
cachefiles: flush all requests after setting CACHEFILES_DEAD
In ondemand mode, when the daemon is processing an open request, if the
kernel flags the cache as CACHEFILES_DEAD, the cachefiles_daemon_write()
will always return -EIO, so the daemon can't pass the copen to the kernel.
Then the kernel process that is waiting for the copen triggers a hung_task.
Since the DEAD state is irreversible, it can only be exited by closing
/dev/cachefiles. Therefore, after calling cachefiles_io_error() to mark
the cache as CACHEFILES_DEAD, if in ondemand mode, flush all requests to
avoid the above hungtask. We may still be able to read some of the cached
data before closing the fd of /dev/cachefiles.
Note that this relies on the patch that adds reference counting to the req,
otherwise it may UAF. |
| In the Linux kernel, the following vulnerability has been resolved:
wifi: iwlwifi: mvm: check n_ssids before accessing the ssids
In some versions of cfg80211, the ssids poinet might be a valid one even
though n_ssids is 0. Accessing the pointer in this case will cuase an
out-of-bound access. Fix this by checking n_ssids first. |
| In the Linux kernel, the following vulnerability has been resolved:
xhci: Handle TD clearing for multiple streams case
When multiple streams are in use, multiple TDs might be in flight when
an endpoint is stopped. We need to issue a Set TR Dequeue Pointer for
each, to ensure everything is reset properly and the caches cleared.
Change the logic so that any N>1 TDs found active for different streams
are deferred until after the first one is processed, calling
xhci_invalidate_cancelled_tds() again from xhci_handle_cmd_set_deq() to
queue another command until we are done with all of them. Also change
the error/"should never happen" paths to ensure we at least clear any
affected TDs, even if we can't issue a command to clear the hardware
cache, and complain loudly with an xhci_warn() if this ever happens.
This problem case dates back to commit e9df17eb1408 ("USB: xhci: Correct
assumptions about number of rings per endpoint.") early on in the XHCI
driver's life, when stream support was first added.
It was then identified but not fixed nor made into a warning in commit
674f8438c121 ("xhci: split handling halted endpoints into two steps"),
which added a FIXME comment for the problem case (without materially
changing the behavior as far as I can tell, though the new logic made
the problem more obvious).
Then later, in commit 94f339147fc3 ("xhci: Fix failure to give back some
cached cancelled URBs."), it was acknowledged again.
[Mathias: commit 94f339147fc3 ("xhci: Fix failure to give back some cached
cancelled URBs.") was a targeted regression fix to the previously mentioned
patch. Users reported issues with usb stuck after unmounting/disconnecting
UAS devices. This rolled back the TD clearing of multiple streams to its
original state.]
Apparently the commit author was aware of the problem (yet still chose
to submit it): It was still mentioned as a FIXME, an xhci_dbg() was
added to log the problem condition, and the remaining issue was mentioned
in the commit description. The choice of making the log type xhci_dbg()
for what is, at this point, a completely unhandled and known broken
condition is puzzling and unfortunate, as it guarantees that no actual
users would see the log in production, thereby making it nigh
undebuggable (indeed, even if you turn on DEBUG, the message doesn't
really hint at there being a problem at all).
It took me *months* of random xHC crashes to finally find a reliable
repro and be able to do a deep dive debug session, which could all have
been avoided had this unhandled, broken condition been actually reported
with a warning, as it should have been as a bug intentionally left in
unfixed (never mind that it shouldn't have been left in at all).
> Another fix to solve clearing the caches of all stream rings with
> cancelled TDs is needed, but not as urgent.
3 years after that statement and 14 years after the original bug was
introduced, I think it's finally time to fix it. And maybe next time
let's not leave bugs unfixed (that are actually worse than the original
bug), and let's actually get people to review kernel commits please.
Fixes xHC crashes and IOMMU faults with UAS devices when handling
errors/faults. Easiest repro is to use `hdparm` to mark an early sector
(e.g. 1024) on a disk as bad, then `cat /dev/sdX > /dev/null` in a loop.
At least in the case of JMicron controllers, the read errors end up
having to cancel two TDs (for two queued requests to different streams)
and the one that didn't get cleared properly ends up faulting the xHC
entirely when it tries to access DMA pages that have since been unmapped,
referred to by the stale TDs. This normally happens quickly (after two
or three loops). After this fix, I left the `cat` in a loop running
overnight and experienced no xHC failures, with all read errors
recovered properly. Repro'd and tested on an Apple M1 Mac Mini
(dwc3 host).
On systems without an IOMMU, this bug would instead silently corrupt
freed memory, making this a
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