linux-stable.git/block, branch v7.1.3

blk-cgroup: fix UAF in __blkcg_rstat_flush()

2026-07-04T11:45:06+00:00

commit 0ab5ee5a1badb58cbb2242617cb01a4972b1f2a2 upstream.

When multiple blkgs in the same blkcg are released concurrently,
a use-after-free can occur. The race happens when one blkg's
__blkcg_rstat_flush() removes another blkg's iostat entries via
llist_del_all(). The second blkg sees an empty list and proceeds
to free itself while the first is still iterating over its entries.

Move the flush from __blkg_release() (RCU callback) to blkg_release()
(before call_rcu). This ensures the RCU grace period waits for any
concurrent flush's rcu_read_lock() section to complete before freeing.

Cc: stable@vger.kernel.org
Cc: Jay Shin 
Cc: Tejun Heo 
Cc: Waiman Long 
Fixes: 20cb1c2fb756 ("blk-cgroup: Flush stats before releasing blkcg_gq")
Reported-by: coregee2000@gmail.com
Closes: https://lore.kernel.org/linux-block/CAHPqNmwT9oRpem3J3erS_W0uSQND47LGGSBsNxP8E6uSUish1w@mail.gmail.com/
Signed-off-by: Ming Lei 
Tested-by: Jose Fernandez (Anthropic) 
Link: https://patch.msgid.link/20260205155425.342084-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

block: Avoid mounting the bdev pseudo-filesystem in userspace

2026-07-04T11:45:05+00:00

commit f73aa66dffcb8e61e78f01b56163ec16a15d06d2 upstream.

The bdev pseudo-filesystem is an internal kernel filesystem with which
userspace should not interfere. Unregister it so that userspace cannot
even attempt to mount it.

This fixes a bug [1] that occurs when attempting to access files,
because the system call move_mount() uses pointers declared in the
inode_operations structure, which for the bdev pseudo-filesystem
are always equal to 0. `inode->i_op = &empty_iops;`

[1]

 BUG: kernel NULL pointer dereference, address: 0000000000000000
 #PF: supervisor instruction fetch in kernel mode
 #PF: error_code(0x0010) - not-present page
 PGD 23380067 P4D 23380067 PUD 23381067 PMD 0
 Oops: 0010 [#1] PREEMPT SMP KASAN NOPTI
 CPU: 2 PID: 17125 Comm: syz-executor.0 Not tainted 6.1.155-syzkaller-00350-g84221fde2681 #0
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
 RIP: 0010:0x0

 Call Trace:
 
 lookup_open.isra.0+0x700/0x1180 fs/namei.c:3460
 open_last_lookups fs/namei.c:3550 [inline]
 path_openat+0x953/0x2700 fs/namei.c:3780
 do_filp_open+0x1c5/0x410 fs/namei.c:3810
 do_sys_openat2+0x171/0x4d0 fs/open.c:1318
 do_sys_open fs/open.c:1334 [inline]
 __do_sys_openat fs/open.c:1350 [inline]
 __se_sys_openat fs/open.c:1345 [inline]
 __x64_sys_openat+0x13c/0x1f0 fs/open.c:1345
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x6e/0xd8

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Link: https://lore.kernel.org/all/20131010004732.GJ13318@ZenIV.linux.org.uk/T/#
Cc: stable@vger.kernel.org
Signed-off-by: Denis Arefev 
Reviewed-by: Christoph Hellwig 
Link: https://patch.msgid.link/20260521072857.5078-1-arefev@swemel.ru
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

Merge tag 'block-7.1-20260529' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux

2026-05-29T17:41:07+00:00

Pull block fix from Jens Axboe:
 "Just a single fix for the block side, making a slight tweak to a fix
  from this cycle"

* tag 'block-7.1-20260529' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux:
  blk-mq: reinsert cached request to the list

blk-mq: reinsert cached request to the list

2026-05-26T21:05:30+00:00

A previous commit removed an optimization out of caution for a scenario
that turns out not to be real: all the "queue_exit" goto's are safe to
reinsert the request into the cached_rq's plug list as they are either
from a non-blocking path, or a successful merge that already holds the
queue reference. This optimization is most needed for small sequential
workloads that successfully merge into larger requests.

Fixes: dc278e9bf2b9 ("blk-mq: pop cached request if it is usable")
Suggested-by: Ming Lei 
Suggested-by: Christoph Hellwig 
Signed-off-by: Keith Busch 
Reviewed-by: Chaitanya Kulkarni 
Link: https://patch.msgid.link/20260526153531.2365935-1-kbusch@meta.com
Signed-off-by: Jens Axboe

Merge tag 'cgroup-for-7.1-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2026-05-22T23:28:47+00:00

Pull cgroup fixes from Tejun Heo:
 "Two rstat fixes:

   - Out-of-bounds access in the css_rstat_updated() BPF kfunc when
     called with an unchecked user-supplied cpu

   - Over-strict NMI guard after the recent switch to try_cmpxchg left
     sparc and ppc64 unable to queue rstat updates from NMI"

* tag 'cgroup-for-7.1-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: rstat: relax NMI guard after switch to try_cmpxchg
  cgroup/rstat: validate cpu before css_rstat_cpu() access

block: avoid use-after-free in disk_free_zone_resources()

2026-05-22T14:01:52+00:00

The function disk_update_zone_resources() may call
disk_free_zone_resources() in case of error, and following this,
blk_revalidate_disk_zones() will again calls disk_free_zone_resources() if
disk_update_zone_resources() failed. If a zone worker thread is being used
(which is the default for a rotational media zoned device),
disk_free_zone_resources() will try to stop the zone worker thread twice
because disk->zone_wplugs_worker is not reset to NULL when the worker
thread is stopped the first time.

In disk_free_zone_resources(), fix this by correctly clearing
disk->zone_wplugs_worker to NULL when the worker thread is stopped.

And while at it, since disk_free_zone_resources() is always called after a
failed call to disk_update_zone_resources(), remove the unnecessary call
to disk_free_zone_resources() in disk_update_zone_resources().

Fixes: 1365b6904fd0 ("block: allow submitting all zone writes from a single context")
Signed-off-by: Damien Le Moal 
Reviewed-by: Christoph Hellwig 
Link: https://patch.msgid.link/20260522115622.588535-1-dlemoal@kernel.org
Signed-off-by: Jens Axboe

blk-mq: pop cached request if it is usable

2026-05-21T19:04:11+00:00

When submitting a bio to blk-mq, if the task should sleep after peeking
a cached request, but before it pops it, the plug flushes and calls
blk_mq_free_plug_rqs, freeing the cached_rqs. This creates a
use-after-free bug. Fix this by popping the cached request before any
possible blocking calls if it is suitable for use.

Popping this request first holds a queue reference, so avoid any
serialization races with queue freezes and can safely proceed with
dispatching that request to the driver. This potentially increases a
timing window from when a driver wants to freeze its queue to when
requests stop being dispatched. That scenario is off the fast path
though, and drivers need to appropriately handle requests during a
freeze request anyway.

The downside is the popped element needs to be individually freed when
we performed a bio plug merge. The cached request would have had to be
freed later anyway, but this patch does it inline with building the plug
list instead of after flushing it.

Fixes: b0077e269f6c1 ("blk-mq: make sure active queue usage is held for bio_integrity_prep()")
Fixes: 7b4f36cd22a65 ("block: ensure we hold a queue reference when using queue limits")
Signed-off-by: Keith Busch 
Link: https://patch.msgid.link/20260521190253.242065-1-kbusch@meta.com
Signed-off-by: Jens Axboe

bio-integrity-fs: pass data iter to bio_integrity_verify()

2026-05-19T17:38:21+00:00

bio_integrity_verify() expects the passed struct bvec_iter to be an
iterator over bio data, not integrity. So construct a separate data
bvec_iter without the bio_integrity_bytes() conversion and pass it to
bio_integrity_verify() instead of bip_iter.

Fixes: 0bde8a12b554 ("block: add fs_bio_integrity helpers")
Signed-off-by: Caleb Sander Mateos 
Reviewed-by: Anuj Gupta 
Reviewed-by: Christoph Hellwig 
Link: https://patch.msgid.link/20260513182924.1753582-1-csander@purestorage.com
Signed-off-by: Jens Axboe

cgroup/rstat: validate cpu before css_rstat_cpu() access

2026-05-18T19:31:52+00:00

css_rstat_updated() is exposed as a BPF kfunc and accepts a
caller-provided cpu argument. The function uses cpu for per-cpu rstat
lookups without checking whether it refers to a valid possible CPU.

A BPF iter/cgroup program with CAP_BPF and CAP_PERFMON can pass an
invalid cpu value. On an unfixed UBSCAN_BOUNDS test kernel, cpu ==
0x7fffffff triggers:

  UBSAN: array-index-out-of-bounds in kernel/cgroup/rstat.c:31:9
  index 2147483647 is out of range for type 'long unsigned int [64]'
  Call Trace:
    css_rstat_updated
    bpf_iter_run_prog
    cgroup_iter_seq_show
    bpf_seq_read

Add cpu validation to the BPF-facing css_rstat_updated() kfunc and
move the common implementation to __css_rstat_updated() for in-kernel
callers.

Fixes: a319185be9f5 ("cgroup: bpf: enable bpf programs to integrate with rstat")
Signed-off-by: Qing Ming 
Signed-off-by: Tejun Heo

block: align down bounces bios

2026-05-13T19:55:18+00:00

Just like for the extract user pages path, we need to align down the
size to the supported boundary.

Fixes: 8dd5e7c75d7b ("block: add helpers to bounce buffer an iov_iter into bios")
Signed-off-by: Christoph Hellwig 
Reviewed-by: Hannes Reinecke 
Link: https://patch.msgid.link/20260507050153.1298375-3-hch@lst.de
Signed-off-by: Jens Axboe