linux-stable.git/block, branch v6.6.63

block: Fix elevator_get_default() checking for NULL q->tag_set

2024-11-17T14:08:56+00:00

[ Upstream commit b402328a24ee7193a8ab84277c0c90ae16768126 ]

elevator_get_default() and elv_support_iosched() both check for whether
or not q->tag_set is non-NULL, however it's not possible for them to be
NULL. This messes up some static checkers, as the checking of tag_set
isn't consistent.

Remove the checks, which both simplifies the logic and avoids checker
errors.

Signed-off-by: SurajSonawane2415 
Link: https://lore.kernel.org/r/20241007111416.13814-1-surajsonawane0215@gmail.com
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

block: fix sanity checks in blk_rq_map_user_bvec

2024-11-08T15:28:24+00:00

[ Upstream commit 2ff949441802a8d076d9013c7761f63e8ae5a9bd ]

blk_rq_map_user_bvec contains a check bytes + bv->bv_len > nr_iter which
causes unnecessary failures in NVMe passthrough I/O, reproducible as
follows:

- register a 2 page, page-aligned buffer against a ring
- use that buffer to do a 1 page io_uring NVMe passthrough read

The second (i = 1) iteration of the loop in blk_rq_map_user_bvec will
then have nr_iter == 1 page, bytes == 1 page, bv->bv_len == 1 page, so
the check bytes + bv->bv_len > nr_iter will succeed, causing the I/O to
fail. This failure is unnecessary, as when the check succeeds, it means
we've checked the entire buffer that will be used by the request - i.e.
blk_rq_map_user_bvec should complete successfully. Therefore, terminate
the loop early and return successfully when the check bytes + bv->bv_len
> nr_iter succeeds.

While we're at it, also remove the check that all segments in the bvec
are single-page. While this seems to be true for all users of the
function, it doesn't appear to be required anywhere downstream.

CC: stable@vger.kernel.org
Signed-off-by: Xinyu Zhang 
Co-developed-by: Uday Shankar 
Signed-off-by: Uday Shankar 
Fixes: 37987547932c ("block: extend functionality to map bvec iterator")
Link: https://lore.kernel.org/r/20241023211519.4177873-1-ushankar@purestorage.com
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

blk-rq-qos: fix crash on rq_qos_wait vs. rq_qos_wake_function race

2024-10-22T13:46:27+00:00

commit e972b08b91ef48488bae9789f03cfedb148667fb upstream.

We're seeing crashes from rq_qos_wake_function that look like this:

  BUG: unable to handle page fault for address: ffffafe180a40084
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 100000067 P4D 100000067 PUD 10027c067 PMD 10115d067 PTE 0
  Oops: Oops: 0002 [#1] PREEMPT SMP PTI
  CPU: 17 UID: 0 PID: 0 Comm: swapper/17 Not tainted 6.12.0-rc3-00013-geca631b8fe80 #11
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
  RIP: 0010:_raw_spin_lock_irqsave+0x1d/0x40
  Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 0f 1f 44 00 00 41 54 9c 41 5c fa 65 ff 05 62 97 30 4c 31 c0 ba 01 00 00 00  0f b1 17 75 0a 4c 89 e0 41 5c c3 cc cc cc cc 89 c6 e8 2c 0b 00
  RSP: 0018:ffffafe180580ca0 EFLAGS: 00010046
  RAX: 0000000000000000 RBX: ffffafe180a3f7a8 RCX: 0000000000000011
  RDX: 0000000000000001 RSI: 0000000000000003 RDI: ffffafe180a40084
  RBP: 0000000000000000 R08: 00000000001e7240 R09: 0000000000000011
  R10: 0000000000000028 R11: 0000000000000888 R12: 0000000000000002
  R13: ffffafe180a40084 R14: 0000000000000000 R15: 0000000000000003
  FS:  0000000000000000(0000) GS:ffff9aaf1f280000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: ffffafe180a40084 CR3: 000000010e428002 CR4: 0000000000770ef0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  PKRU: 55555554
  Call Trace:
   
   try_to_wake_up+0x5a/0x6a0
   rq_qos_wake_function+0x71/0x80
   __wake_up_common+0x75/0xa0
   __wake_up+0x36/0x60
   scale_up.part.0+0x50/0x110
   wb_timer_fn+0x227/0x450
   ...

So rq_qos_wake_function() calls wake_up_process(data->task), which calls
try_to_wake_up(), which faults in raw_spin_lock_irqsave(&p->pi_lock).

p comes from data->task, and data comes from the waitqueue entry, which
is stored on the waiter's stack in rq_qos_wait(). Analyzing the core
dump with drgn, I found that the waiter had already woken up and moved
on to a completely unrelated code path, clobbering what was previously
data->task. Meanwhile, the waker was passing the clobbered garbage in
data->task to wake_up_process(), leading to the crash.

What's happening is that in between rq_qos_wake_function() deleting the
waitqueue entry and calling wake_up_process(), rq_qos_wait() is finding
that it already got a token and returning. The race looks like this:

rq_qos_wait()                           rq_qos_wake_function()
==============================================================
prepare_to_wait_exclusive()
                                        data->got_token = true;
                                        list_del_init(&curr->entry);
if (data.got_token)
        break;
finish_wait(&rqw->wait, &data.wq);
  ^- returns immediately because
     list_empty_careful(&wq_entry->entry)
     is true
... return, go do something else ...
                                        wake_up_process(data->task)
                                          (NO LONGER VALID!)-^

Normally, finish_wait() is supposed to synchronize against the waker.
But, as noted above, it is returning immediately because the waitqueue
entry has already been removed from the waitqueue.

The bug is that rq_qos_wake_function() is accessing the waitqueue entry
AFTER deleting it. Note that autoremove_wake_function() wakes the waiter
and THEN deletes the waitqueue entry, which is the proper order.

Fix it by swapping the order. We also need to use
list_del_init_careful() to match the list_empty_careful() in
finish_wait().

Fixes: 38cfb5a45ee0 ("blk-wbt: improve waking of tasks")
Cc: stable@vger.kernel.org
Signed-off-by: Omar Sandoval 
Acked-by: Tejun Heo 
Reviewed-by: Johannes Thumshirn 
Link: https://lore.kernel.org/r/d3bee2463a67b1ee597211823bf7ad3721c26e41.1729014591.git.osandov@fb.com
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

blk_iocost: fix more out of bound shifts

2024-10-10T09:57:24+00:00

[ Upstream commit 9bce8005ec0dcb23a58300e8522fe4a31da606fa ]

Recently running UBSAN caught few out of bound shifts in the
ioc_forgive_debts() function:

UBSAN: shift-out-of-bounds in block/blk-iocost.c:2142:38
shift exponent 80 is too large for 64-bit type 'u64' (aka 'unsigned long
long')
...
UBSAN: shift-out-of-bounds in block/blk-iocost.c:2144:30
shift exponent 80 is too large for 64-bit type 'u64' (aka 'unsigned long
long')
...
Call Trace:

dump_stack_lvl+0xca/0x130
__ubsan_handle_shift_out_of_bounds+0x22c/0x280
? __lock_acquire+0x6441/0x7c10
ioc_timer_fn+0x6cec/0x7750
? blk_iocost_init+0x720/0x720
? call_timer_fn+0x5d/0x470
call_timer_fn+0xfa/0x470
? blk_iocost_init+0x720/0x720
__run_timer_base+0x519/0x700
...

Actual impact of this issue was not identified but I propose to fix the
undefined behaviour.
The proposed fix to prevent those out of bound shifts consist of
precalculating exponent before using it the shift operations by taking
min value from the actual exponent and maximum possible number of bits.

Reported-by: Breno Leitao 
Signed-off-by: Konstantin Ovsepian 
Acked-by: Tejun Heo 
Link: https://lore.kernel.org/r/20240822154137.2627818-1-ovs@ovs.to
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

block: fix potential invalid pointer dereference in blk_add_partition

2024-10-04T14:29:01+00:00

[ Upstream commit 26e197b7f9240a4ac301dd0ad520c0c697c2ea7d ]

The blk_add_partition() function initially used a single if-condition
(IS_ERR(part)) to check for errors when adding a partition. This was
modified to handle the specific case of -ENXIO separately, allowing the
function to proceed without logging the error in this case. However,
this change unintentionally left a path where md_autodetect_dev()
could be called without confirming that part is a valid pointer.

This commit separates the error handling logic by splitting the
initial if-condition, improving code readability and handling specific
error scenarios explicitly. The function now distinguishes the general
error case from -ENXIO without altering the existing behavior of
md_autodetect_dev() calls.

Fixes: b72053072c0b (block: allow partitions on host aware zone devices)
Signed-off-by: Riyan Dhiman 
Reviewed-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/20240911132954.5874-1-riyandhiman14@gmail.com
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

block: print symbolic error name instead of error code

2024-10-04T14:29:01+00:00

[ Upstream commit 25c1772a0493463408489b1fae65cf77fe46cac1 ]

Utilize the %pe print specifier to get the symbolic error name as a
string (i.e "-ENOMEM") in the log message instead of the error code to
increase its readablility.

This change was suggested in
https://lore.kernel.org/all/92972476-0b1f-4d0a-9951-af3fc8bc6e65@suswa.mountain/

Signed-off-by: Christian Heusel 
Reviewed-by: Chaitanya Kulkarni 
Link: https://lore.kernel.org/r/20240111231521.1596838-1-christian@heusel.eu
Signed-off-by: Jens Axboe 
Stable-dep-of: 26e197b7f924 ("block: fix potential invalid pointer dereference in blk_add_partition")
Signed-off-by: Sasha Levin

block, bfq: fix procress reference leakage for bfqq in merge chain

2024-10-04T14:29:00+00:00

[ Upstream commit 73aeab373557fa6ee4ae0b742c6211ccd9859280 ]

Original state:

        Process 1       Process 2       Process 3       Process 4
         (BIC1)          (BIC2)          (BIC3)          (BIC4)
          Λ                |               |               |
           \--------------\ \-------------\ \-------------\|
                           V               V               V
          bfqq1--------->bfqq2---------->bfqq3----------->bfqq4
    ref    0               1               2               4

After commit 0e456dba86c7 ("block, bfq: choose the last bfqq from merge
chain in bfq_setup_cooperator()"), if P1 issues a new IO:

Without the patch:

        Process 1       Process 2       Process 3       Process 4
         (BIC1)          (BIC2)          (BIC3)          (BIC4)
          Λ                |               |               |
           \------------------------------\ \-------------\|
                                           V               V
          bfqq1--------->bfqq2---------->bfqq3----------->bfqq4
    ref    0               0               2               4

bfqq3 will be used to handle IO from P1, this is not expected, IO
should be redirected to bfqq4;

With the patch:

          -------------------------------------------
          |                                         |
        Process 1       Process 2       Process 3   |   Process 4
         (BIC1)          (BIC2)          (BIC3)     |    (BIC4)
                           |               |        |      |
                            \-------------\ \-------------\|
                                           V               V
          bfqq1--------->bfqq2---------->bfqq3----------->bfqq4
    ref    0               0               2               4

IO is redirected to bfqq4, however, procress reference of bfqq3 is still
2, while there is only P2 using it.

Fix the problem by calling bfq_merge_bfqqs() for each bfqq in the merge
chain. Also change bfqq_merge_bfqqs() to return new_bfqq to simplify
code.

Fixes: 0e456dba86c7 ("block, bfq: choose the last bfqq from merge chain in bfq_setup_cooperator()")
Signed-off-by: Yu Kuai 
Link: https://lore.kernel.org/r/20240909134154.954924-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

block, bfq: fix uaf for accessing waker_bfqq after splitting

2024-10-04T14:29:00+00:00

[ Upstream commit 1ba0403ac6447f2d63914fb760c44a3b19c44eaf ]

After commit 42c306ed7233 ("block, bfq: don't break merge chain in
bfq_split_bfqq()"), if the current procress is the last holder of bfqq,
the bfqq can be freed after bfq_split_bfqq(). Hence recored the bfqq and
then access bfqq->waker_bfqq may trigger UAF. What's more, the waker_bfqq
may in the merge chain of bfqq, hence just recored waker_bfqq is still
not safe.

Fix the problem by adding a helper bfq_waker_bfqq() to check if
bfqq->waker_bfqq is in the merge chain, and current procress is the only
holder.

Fixes: 42c306ed7233 ("block, bfq: don't break merge chain in bfq_split_bfqq()")
Signed-off-by: Yu Kuai 
Link: https://lore.kernel.org/r/20240909134154.954924-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

block, bfq: don't break merge chain in bfq_split_bfqq()

2024-10-04T14:29:00+00:00

[ Upstream commit 42c306ed723321af4003b2a41bb73728cab54f85 ]

Consider the following scenario:

    Process 1       Process 2       Process 3       Process 4
     (BIC1)          (BIC2)          (BIC3)          (BIC4)
      Λ               |               |                |
       \-------------\ \-------------\ \--------------\|
                      V               V                V
      bfqq1--------->bfqq2---------->bfqq3----------->bfqq4
ref    0              1               2                4

If Process 1 issue a new IO and bfqq2 is found, and then bfq_init_rq()
decide to spilt bfqq2 by bfq_split_bfqq(). Howerver, procress reference
of bfqq2 is 1 and bfq_split_bfqq() just clear the coop flag, which will
break the merge chain.

Expected result: caller will allocate a new bfqq for BIC1

    Process 1       Process 2       Process 3       Process 4
     (BIC1)          (BIC2)          (BIC3)          (BIC4)
                      |               |                |
                       \-------------\ \--------------\|
                                      V                V
      bfqq1--------->bfqq2---------->bfqq3----------->bfqq4
ref    0              0               1                3

Since the condition is only used for the last bfqq4 when the previous
bfqq2 and bfqq3 are already splited. Fix the problem by checking if
bfqq is the last one in the merge chain as well.

Fixes: 36eca8948323 ("block, bfq: add Early Queue Merge (EQM)")
Signed-off-by: Yu Kuai 
Link: https://lore.kernel.org/r/20240902130329.3787024-4-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

block, bfq: choose the last bfqq from merge chain in bfq_setup_cooperator()

2024-10-04T14:29:00+00:00

[ Upstream commit 0e456dba86c7f9a19792204a044835f1ca2c8dbb ]

Consider the following merge chain:

Process 1       Process 2       Process 3	Process 4
 (BIC1)          (BIC2)          (BIC3)		 (BIC4)
  Λ                |               |               |
   \--------------\ \-------------\ \-------------\|
                   V               V		   V
  bfqq1--------->bfqq2---------->bfqq3----------->bfqq4

IO from Process 1 will get bfqf2 from BIC1 first, then
bfq_setup_cooperator() will found bfqq2 already merged to bfqq3 and then
handle this IO from bfqq3. However, the merge chain can be much deeper
and bfqq3 can be merged to other bfqq as well.

Fix this problem by iterating to the last bfqq in
bfq_setup_cooperator().

Fixes: 36eca8948323 ("block, bfq: add Early Queue Merge (EQM)")
Signed-off-by: Yu Kuai 
Link: https://lore.kernel.org/r/20240902130329.3787024-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin