Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.
This lack of consistentcy cannot be addressed without refactoring the API.
alloc_workqueue() treats all queues as per-CPU by default, while unbound
workqueues must opt-in via WQ_UNBOUND.
This default is suboptimal: most workloads benefit from unbound queues,
allowing the scheduler to place worker threads where they’re needed and
reducing noise when CPUs are isolated.
This default is suboptimal: most workloads benefit from unbound queues,
allowing the scheduler to place worker threads where they’re needed and
reducing noise when CPUs are isolated.
This patch adds a new WQ_PERCPU flag to explicitly request the use of
the per-CPU behavior. Both flags coexist for one release cycle to allow
callers to transition their calls.
Once migration is complete, WQ_UNBOUND can be removed and unbound will
become the implicit default.
With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
must now use WQ_PERCPU.
All existing users have been updated accordingly.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.
This lack of consistentcy cannot be addressed without refactoring the API.
system_unbound_wq should be the default workqueue so as not to enforce
locality constraints for random work whenever it's not required.
Adding system_dfl_wq to encourage its use when unbound work should be used.
queue_work() / queue_delayed_work() / mod_delayed_work() will now use the
new unbound wq: whether the user still use the old wq a warn will be
printed along with a wq redirect to the new one.
The old system_unbound_wq will be kept for a few release cycles.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
When seq_nr wraps around, the next reorder job with seq 0 is hashed to
the first CPU in padata_do_serial(). Correspondingly, need reset pd->cpu
to the first one when pd->processed wraps around. Otherwise, if the
number of used CPUs is not a power of 2, padata_find_next() will be
checking a wrong list, hence deadlock.
Fixes: 6fc4dbcf02 ("padata: Replace delayed timer with immediate workqueue in padata_reorder")
Cc: <stable@vger.kernel.org>
Signed-off-by: Xiao Liang <shaw.leon@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
padata_do_parallel() and padata_index_to_cpu() duplicate cpumask_nth().
Fix both and use the generic helper.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
There is a race condition/UAF in padata_reorder that goes back
to the initial commit. A reference count is taken at the start
of the process in padata_do_parallel, and released at the end in
padata_serial_worker.
This reference count is (and only is) required for padata_replace
to function correctly. If padata_replace is never called then
there is no issue.
In the function padata_reorder which serves as the core of padata,
as soon as padata is added to queue->serial.list, and the associated
spin lock released, that padata may be processed and the reference
count on pd would go away.
Fix this by getting the next padata before the squeue->serial lock
is released.
In order to make this possible, simplify padata_reorder by only
calling it once the next padata arrives.
Fixes: 16295bec63 ("padata: Generic parallelization/serialization interface")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
A recent patch that addressed a UAF introduced a reference count leak:
the parallel_data refcount is incremented unconditionally, regardless
of the return value of queue_work(). If the work item is already queued,
the incremented refcount is never decremented.
Fix this by checking the return value of queue_work() and decrementing
the refcount when necessary.
Resolves:
Unreferenced object 0xffff9d9f421e3d80 (size 192):
comm "cryptomgr_probe", pid 157, jiffies 4294694003
hex dump (first 32 bytes):
80 8b cf 41 9f 9d ff ff b8 97 e0 89 ff ff ff ff ...A............
d0 97 e0 89 ff ff ff ff 19 00 00 00 1f 88 23 00 ..............#.
backtrace (crc 838fb36):
__kmalloc_cache_noprof+0x284/0x320
padata_alloc_pd+0x20/0x1e0
padata_alloc_shell+0x3b/0xa0
0xffffffffc040a54d
cryptomgr_probe+0x43/0xc0
kthread+0xf6/0x1f0
ret_from_fork+0x2f/0x50
ret_from_fork_asm+0x1a/0x30
Fixes: dd7d37ccf6 ("padata: avoid UAF for reorder_work")
Cc: <stable@vger.kernel.org>
Signed-off-by: Dominik Grzegorzek <dominik.grzegorzek@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Calling cpumask_next_wrap_old() with starting CPU == -1 effectively means
the request to find next CPU, wrapping around if needed.
cpumask_next_wrap() is the proper replacement for that.
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
The next patch aligns implementation of cpumask_next_wrap() with the
find_next_bit_wrap(), and it changes function signature.
To make the transition smooth, this patch deprecates current
implementation by adding an _old suffix. The following patches switch
current users to the new implementation one by one.
No functional changes were intended.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Although the previous patch can avoid ps and ps UAF for _do_serial, it
can not avoid potential UAF issue for reorder_work. This issue can
happen just as below:
crypto_request crypto_request crypto_del_alg
padata_do_serial
...
padata_reorder
// processes all remaining
// requests then breaks
while (1) {
if (!padata)
break;
...
}
padata_do_serial
// new request added
list_add
// sees the new request
queue_work(reorder_work)
padata_reorder
queue_work_on(squeue->work)
...
<kworker context>
padata_serial_worker
// completes new request,
// no more outstanding
// requests
crypto_del_alg
// free pd
<kworker context>
invoke_padata_reorder
// UAF of pd
To avoid UAF for 'reorder_work', get 'pd' ref before put 'reorder_work'
into the 'serial_wq' and put 'pd' ref until the 'serial_wq' finish.
Fixes: bbefa1dd6a ("crypto: pcrypt - Avoid deadlock by using per-instance padata queues")
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
A bug was found when run ltp test:
BUG: KASAN: slab-use-after-free in padata_find_next+0x29/0x1a0
Read of size 4 at addr ffff88bbfe003524 by task kworker/u113:2/3039206
CPU: 0 PID: 3039206 Comm: kworker/u113:2 Kdump: loaded Not tainted 6.6.0+
Workqueue: pdecrypt_parallel padata_parallel_worker
Call Trace:
<TASK>
dump_stack_lvl+0x32/0x50
print_address_description.constprop.0+0x6b/0x3d0
print_report+0xdd/0x2c0
kasan_report+0xa5/0xd0
padata_find_next+0x29/0x1a0
padata_reorder+0x131/0x220
padata_parallel_worker+0x3d/0xc0
process_one_work+0x2ec/0x5a0
If 'mdelay(10)' is added before calling 'padata_find_next' in the
'padata_reorder' function, this issue could be reproduced easily with
ltp test (pcrypt_aead01).
This can be explained as bellow:
pcrypt_aead_encrypt
...
padata_do_parallel
refcount_inc(&pd->refcnt); // add refcnt
...
padata_do_serial
padata_reorder // pd
while (1) {
padata_find_next(pd, true); // using pd
queue_work_on
...
padata_serial_worker crypto_del_alg
padata_put_pd_cnt // sub refcnt
padata_free_shell
padata_put_pd(ps->pd);
// pd is freed
// loop again, but pd is freed
// call padata_find_next, UAF
}
In the padata_reorder function, when it loops in 'while', if the alg is
deleted, the refcnt may be decreased to 0 before entering
'padata_find_next', which leads to UAF.
As mentioned in [1], do_serial is supposed to be called with BHs disabled
and always happen under RCU protection, to address this issue, add
synchronize_rcu() in 'padata_free_shell' wait for all _do_serial calls
to finish.
[1] https://lore.kernel.org/all/20221028160401.cccypv4euxikusiq@parnassus.localdomain/
[2] https://lore.kernel.org/linux-kernel/jfjz5d7zwbytztackem7ibzalm5lnxldi2eofeiczqmqs2m7o6@fq426cwnjtkm/
Fixes: b128a30409 ("padata: allocate workqueue internally")
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Qu Zicheng <quzicheng@huawei.com>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
padata_sysfs_store() was copied from padata_sysfs_show() but this check
was not adapted. Today there is no attribute which can fail this
check, but if there is one it may as well be correct.
Fixes: 5e017dc3f8 ("padata: Added sysfs primitives to padata subsystem")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
In commit 24cc57d8fa ("padata: Honor the caller's alignment in case of
chunk_size 0"), the line 'ps.chunk_size = max(ps.chunk_size, 1ul)' was
added, making 'ps.chunk_size = 1U' redundant and never executed.
Signed-off-by: Zicheng Qu <quzicheng@huawei.com>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
In the case where we are forcing the ps.chunk_size to be at least 1,
we are ignoring the caller's alignment.
Move the forcing of ps.chunk_size to be at least 1 before rounding it
up to caller's alignment, so that caller's alignment is honored.
While at it, use max() to force the ps.chunk_size to be at least 1 to
improve readability.
Fixes: 6d45e1c948 ("padata: Fix possible divide-by-0 panic in padata_mt_helper()")
Signed-off-by: Kamlesh Gurudasani <kamlesh@ti.com>
Acked-by: Waiman Long <longman@redhat.com>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
When submitting more than 2^32 padata objects to padata_do_serial, the
current sorting implementation incorrectly sorts padata objects with
overflowed seq_nr, causing them to be placed before existing objects in
the reorder list. This leads to a deadlock in the serialization process
as padata_find_next cannot match padata->seq_nr and pd->processed
because the padata instance with overflowed seq_nr will be selected
next.
To fix this, we use an unsigned integer wrap around to correctly sort
padata objects in scenarios with integer overflow.
Fixes: bfde23ce20 ("padata: unbind parallel jobs from specific CPUs")
Cc: <stable@vger.kernel.org>
Co-developed-by: Christian Gafert <christian.gafert@rohde-schwarz.com>
Signed-off-by: Christian Gafert <christian.gafert@rohde-schwarz.com>
Co-developed-by: Max Ferger <max.ferger@rohde-schwarz.com>
Signed-off-by: Max Ferger <max.ferger@rohde-schwarz.com>
Signed-off-by: Van Giang Nguyen <vangiang.nguyen@rohde-schwarz.com>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
We are hit with a not easily reproducible divide-by-0 panic in padata.c at
bootup time.
[ 10.017908] Oops: divide error: 0000 1 PREEMPT SMP NOPTI
[ 10.017908] CPU: 26 PID: 2627 Comm: kworker/u1666:1 Not tainted 6.10.0-15.el10.x86_64 #1
[ 10.017908] Hardware name: Lenovo ThinkSystem SR950 [7X12CTO1WW]/[7X12CTO1WW], BIOS [PSE140J-2.30] 07/20/2021
[ 10.017908] Workqueue: events_unbound padata_mt_helper
[ 10.017908] RIP: 0010:padata_mt_helper+0x39/0xb0
:
[ 10.017963] Call Trace:
[ 10.017968] <TASK>
[ 10.018004] ? padata_mt_helper+0x39/0xb0
[ 10.018084] process_one_work+0x174/0x330
[ 10.018093] worker_thread+0x266/0x3a0
[ 10.018111] kthread+0xcf/0x100
[ 10.018124] ret_from_fork+0x31/0x50
[ 10.018138] ret_from_fork_asm+0x1a/0x30
[ 10.018147] </TASK>
Looking at the padata_mt_helper() function, the only way a divide-by-0
panic can happen is when ps->chunk_size is 0. The way that chunk_size is
initialized in padata_do_multithreaded(), chunk_size can be 0 when the
min_chunk in the passed-in padata_mt_job structure is 0.
Fix this divide-by-0 panic by making sure that chunk_size will be at least
1 no matter what the input parameters are.
Link: https://lkml.kernel.org/r/20240806174647.1050398-1-longman@redhat.com
Fixes: 004ed42638 ("padata: add basic support for multithreaded jobs")
Signed-off-by: Waiman Long <longman@redhat.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Waiman Long <longman@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In a high-load arm64 environment, the pcrypt_aead01 test in LTP can lead
to system UAF (Use-After-Free) issues. Due to the lengthy analysis of
the pcrypt_aead01 function call, I'll describe the problem scenario
using a simplified model:
Suppose there's a user of padata named `user_function` that adheres to
the padata requirement of calling `padata_free_shell` after `serial()`
has been invoked, as demonstrated in the following code:
```c
struct request {
struct padata_priv padata;
struct completion *done;
};
void parallel(struct padata_priv *padata) {
do_something();
}
void serial(struct padata_priv *padata) {
struct request *request = container_of(padata,
struct request,
padata);
complete(request->done);
}
void user_function() {
DECLARE_COMPLETION(done)
padata->parallel = parallel;
padata->serial = serial;
padata_do_parallel();
wait_for_completion(&done);
padata_free_shell();
}
```
In the corresponding padata.c file, there's the following code:
```c
static void padata_serial_worker(struct work_struct *serial_work) {
...
cnt = 0;
while (!list_empty(&local_list)) {
...
padata->serial(padata);
cnt++;
}
local_bh_enable();
if (refcount_sub_and_test(cnt, &pd->refcnt))
padata_free_pd(pd);
}
```
Because of the high system load and the accumulation of unexecuted
softirq at this moment, `local_bh_enable()` in padata takes longer
to execute than usual. Subsequently, when accessing `pd->refcnt`,
`pd` has already been released by `padata_free_shell()`, resulting
in a UAF issue with `pd->refcnt`.
The fix is straightforward: add `refcount_dec_and_test` before calling
`padata_free_pd` in `padata_free_shell`.
Fixes: 07928d9bfc ("padata: Remove broken queue flushing")
Signed-off-by: WangJinchao <wangjinchao@xfusion.com>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
We found a hungtask bug in test_aead_vec_cfg as follows:
INFO: task cryptomgr_test:391009 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Call trace:
__switch_to+0x98/0xe0
__schedule+0x6c4/0xf40
schedule+0xd8/0x1b4
schedule_timeout+0x474/0x560
wait_for_common+0x368/0x4e0
wait_for_completion+0x20/0x30
wait_for_completion+0x20/0x30
test_aead_vec_cfg+0xab4/0xd50
test_aead+0x144/0x1f0
alg_test_aead+0xd8/0x1e0
alg_test+0x634/0x890
cryptomgr_test+0x40/0x70
kthread+0x1e0/0x220
ret_from_fork+0x10/0x18
Kernel panic - not syncing: hung_task: blocked tasks
For padata_do_parallel, when the return err is 0 or -EBUSY, it will call
wait_for_completion(&wait->completion) in test_aead_vec_cfg. In normal
case, aead_request_complete() will be called in pcrypt_aead_serial and the
return err is 0 for padata_do_parallel. But, when pinst->flags is
PADATA_RESET, the return err is -EBUSY for padata_do_parallel, and it
won't call aead_request_complete(). Therefore, test_aead_vec_cfg will
hung at wait_for_completion(&wait->completion), which will cause
hungtask.
The problem comes as following:
(padata_do_parallel) |
rcu_read_lock_bh(); |
err = -EINVAL; | (padata_replace)
| pinst->flags |= PADATA_RESET;
err = -EBUSY |
if (pinst->flags & PADATA_RESET) |
rcu_read_unlock_bh() |
return err
In order to resolve the problem, we replace the return err -EBUSY with
-EAGAIN, which means parallel_data is changing, and the caller should call
it again.
v3:
remove retry and just change the return err.
v2:
introduce padata_try_do_parallel() in pcrypt_aead_encrypt and
pcrypt_aead_decrypt to solve the hungtask.
Signed-off-by: Lu Jialin <lujialin4@huawei.com>
Signed-off-by: Guo Zihua <guozihua@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
For multithreaded jobs the computed chunk size is rounded up by the
caller-specified alignment. However, the number of worker threads to
use is computed using the minimum chunk size without taking alignment
into account. A sufficiently large alignment value can result in too
many worker threads being allocated for the job.
Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Since commit ee6d3dd4ed ("driver core: make kobj_type constant.")
the driver core allows the usage of const struct kobj_type.
Take advantage of this to constify the structure definition to prevent
modification at runtime.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Pull Kbuild updates from Masahiro Yamada:
- Support zstd-compressed debug info
- Allow W=1 builds to detect objects shared among multiple modules
- Add srcrpm-pkg target to generate a source RPM package
- Make the -s option detection work for future GNU Make versions
- Add -Werror to KBUILD_CPPFLAGS when CONFIG_WERROR=y
- Allow W=1 builds to detect -Wundef warnings in any preprocessed files
- Raise the minimum supported version of binutils to 2.25
- Use $(intcmp ...) to compare integers if GNU Make >= 4.4 is used
- Use $(file ...) to read a file if GNU Make >= 4.2 is used
- Print error if GNU Make older than 3.82 is used
- Allow modpost to detect section mismatches with Clang LTO
- Include vmlinuz.efi into kernel tarballs for arm64 CONFIG_EFI_ZBOOT=y
* tag 'kbuild-v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (29 commits)
buildtar: fix tarballs with EFI_ZBOOT enabled
modpost: Include '.text.*' in TEXT_SECTIONS
padata: Mark padata_work_init() as __ref
kbuild: ensure Make >= 3.82 is used
kbuild: refactor the prerequisites of the modpost rule
kbuild: change module.order to list *.o instead of *.ko
kbuild: use .NOTINTERMEDIATE for future GNU Make versions
kconfig: refactor Makefile to reduce process forks
kbuild: add read-file macro
kbuild: do not sort after reading modules.order
kbuild: add test-{ge,gt,le,lt} macros
Documentation: raise minimum supported version of binutils to 2.25
kbuild: add -Wundef to KBUILD_CPPFLAGS for W=1 builds
kbuild: move -Werror from KBUILD_CFLAGS to KBUILD_CPPFLAGS
kbuild: Port silent mode detection to future gnu make.
init/version.c: remove #include <generated/utsrelease.h>
firmware_loader: remove #include <generated/utsrelease.h>
modpost: Mark uuid_le type to be suitable only for MEI
kbuild: add ability to make source rpm buildable using koji
kbuild: warn objects shared among multiple modules
...
When building arm64 allmodconfig + ThinLTO with clang and a proposed
modpost update to account for -ffuncton-sections, the following warning
appears:
WARNING: modpost: vmlinux.o: section mismatch in reference: padata_work_init (section: .text.padata_work_init) -> padata_mt_helper (section: .init.text)
WARNING: modpost: vmlinux.o: section mismatch in reference: padata_work_init (section: .text.padata_work_init) -> padata_mt_helper (section: .init.text)
LLVM has optimized padata_work_init() to include the address of
padata_mt_helper() directly because it inlined the other call to
padata_work_init() with padata_parallel_worker(), meaning the remaining
uses of padata_work_init() use padata_mt_helper() as the work_fn
argument. This optimization causes modpost to complain since
padata_work_init() is not __init, whereas padata_mt_helper() is.
Since padata_work_init() is only called from __init code when
padata_mt_helper() is passed as the work_fn argument, mark
padata_work_init() as __ref, which makes it clear to modpost that this
scenario is okay.
Suggested-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Marco Crivellari
Xiao Liang
Yury Norov
Herbert Xu
Dominik Grzegorzek
Chen Ridong
Thomas Weißschuh
Zicheng Qu
Linus Torvalds
Kamlesh Gurudasani
VanGiang Nguyen
Waiman Long
Gang Li Subject: padata: dispatch works on
WangJinchao
Lu Jialin
Anthony Yznaga
Nathan Chancellor