linux-stable.git/fs/sysfs, branch v4.14.331

fs: sysfs_emit_at: Remove PAGE_SIZE alignment check

2023-03-22T12:26:13+00:00

From: Eric Biggers 

[No upstream commit because this fixes a bug in a backport.]

Before upstream commit 59bb47985c1d ("mm, sl[aou]b: guarantee natural
alignment for kmalloc(power-of-two)") which went into v5.4, kmalloc did
*not* always guarantee that PAGE_SIZE allocations are PAGE_SIZE-aligned.

Upstream commit 2efc459d06f1 ("sysfs: Add sysfs_emit and sysfs_emit_at
to format sysfs output") added two WARN()s that trigger when PAGE_SIZE
allocations are not PAGE_SIZE-aligned.  This was backported to old
kernels that don't guarantee PAGE_SIZE alignment.

Commit 10ddfb495232 ("fs: sysfs_emit: Remove PAGE_SIZE alignment check")
in 4.19.y, and its equivalent in 4.14.y and 4.9.y, tried to fix this
bug.  However, only it handled sysfs_emit(), not sysfs_emit_at().

Fix it in sysfs_emit_at() too.

A reproducer is to build the kernel with the following options:

	CONFIG_SLUB=y
	CONFIG_SLUB_DEBUG=y
	CONFIG_SLUB_DEBUG_ON=y
	CONFIG_PM=y
	CONFIG_SUSPEND=y
	CONFIG_PM_WAKELOCKS=y

Then run:

	echo foo > /sys/power/wake_lock && cat /sys/power/wake_lock

Fixes: cb1f69d53ac8 ("sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output")
Reported-by: kernel test robot 
Link: https://lore.kernel.org/r/202303141634.1e64fd76-yujie.liu@intel.com
Signed-off-by: Eric Biggers 
Signed-off-by: Greg Kroah-Hartman

fs: sysfs_emit: Remove PAGE_SIZE alignment check

2022-03-23T08:01:35+00:00

For kernel releases older than 4.20, using the SLUB alloctor will cause
this alignment check to fail as that allocator did NOT align kmalloc
allocations on a PAGE_SIZE boundry.

Remove the check for these older kernels as it is a false-positive and
causes problems on many devices.

Signed-off-by: Lucas Wei 
Signed-off-by: Greg Kroah-Hartman

unfuck sysfs_mount()

2021-06-30T12:48:55+00:00

commit 7b745a4e4051e1bbce40e0b1c2cf636c70583aa4 upstream.

new_sb is left uninitialized in case of early failures in kernfs_mount_ns(),
and while IS_ERR(root) is true in all such cases, using IS_ERR(root) || !new_sb
is not a solution - IS_ERR(root) is true in some cases when new_sb is true.

Make sure new_sb is initialized (and matches the reality) in all cases and
fix the condition for dropping kobj reference - we want it done precisely
in those situations where the reference has not been transferred into a new
super_block instance.

Signed-off-by: Al Viro 
Signed-off-by: Guilherme G. Piccoli 
Signed-off-by: Greg Kroah-Hartman

sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output

2021-03-07T10:27:45+00:00

commit 2efc459d06f1630001e3984854848a5647086232 upstream.

Output defects can exist in sysfs content using sprintf and snprintf.

sprintf does not know the PAGE_SIZE maximum of the temporary buffer
used for outputting sysfs content and it's possible to overrun the
PAGE_SIZE buffer length.

Add a generic sysfs_emit function that knows that the size of the
temporary buffer and ensures that no overrun is done.

Add a generic sysfs_emit_at function that can be used in multiple
call situations that also ensures that no overrun is done.

Validate the output buffer argument to be page aligned.
Validate the offset len argument to be within the PAGE_SIZE buf.

Signed-off-by: Joe Perches 
Link: https://lore.kernel.org/r/884235202216d464d61ee975f7465332c86f76b2.1600285923.git.joe@perches.com
Signed-off-by: Greg Kroah-Hartman

scsi: sysfs: Introduce sysfs_{un,}break_active_protection()

2018-09-05T07:26:41+00:00

commit 2afc9166f79b8f6da5f347f48515215ceee4ae37 upstream.

Introduce these two functions and export them such that the next patch
can add calls to these functions from the SCSI core.

Signed-off-by: Bart Van Assche 
Acked-by: Tejun Heo 
Acked-by: Greg Kroah-Hartman 
Cc: 
Signed-off-by: Martin K. Petersen 
Signed-off-by: Greg Kroah-Hartman

sysfs: symlink: export sysfs_create_link_nowarn()

2018-03-31T16:10:38+00:00

[ Upstream commit 2399ac42e762ab25c58420e25359b2921afdc55f ]

The sysfs_create_link_nowarn() is going to be used in phylib framework in
subsequent patch which can be built as module. Hence, export
sysfs_create_link_nowarn() to avoid build errors.

Cc: Florian Fainelli 
Cc: Andrew Lunn 
Fixes: a3995460491d ("net: phy: Relax error checking on sysfs_create_link()")
Signed-off-by: Grygorii Strashko 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

sysfs: be careful of error returns from ops->show()

2017-04-08T15:33:32+00:00

ops->show() can return a negative error code.
Commit 65da3484d9be ("sysfs: correctly handle short reads on PREALLOC attrs.")
(in v4.4) caused this to be stored in an unsigned 'size_t' variable, so errors
would look like large numbers.
As a result, if an error is returned, sysfs_kf_read() will return the
value of 'count', typically 4096.

Commit 17d0774f8068 ("sysfs: correctly handle read offset on PREALLOC attrs")
(in v4.8) extended this error to use the unsigned large 'len' as a size for
memmove().
Consequently, if ->show returns an error, then the first read() on the
sysfs file will return 4096 and could return uninitialized memory to
user-space.
If the application performs a subsequent read, this will trigger a memmove()
with extremely large count, and is likely to crash the machine is bizarre ways.

This bug can currently only be triggered by reading from an md
sysfs attribute declared with __ATTR_PREALLOC() during the
brief period between when mddev_put() deletes an mddev from
the ->all_mddevs list, and when mddev_delayed_delete() - which is
scheduled on a workqueue - completes.
Before this, an error won't be returned by the ->show()
After this, the ->show() won't be called.

I can reproduce it reliably only by putting delay like
	usleep_range(500000,700000);
early in mddev_delayed_delete(). Then after creating an
md device md0 run
  echo clear > /sys/block/md0/md/array_state; cat /sys/block/md0/md/array_state

The bug can be triggered without the usleep.

Fixes: 65da3484d9be ("sysfs: correctly handle short reads on PREALLOC attrs.")
Fixes: 17d0774f8068 ("sysfs: correctly handle read offset on PREALLOC attrs")
Cc: stable@vger.kernel.org
Signed-off-by: NeilBrown 
Acked-by: Tejun Heo 
Reported-and-tested-by: Miroslav Benes 
Signed-off-by: Greg Kroah-Hartman

Merge branch 'for-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2016-10-14T19:18:50+00:00

Pull cgroup updates from Tejun Heo:

 - tracepoints for basic cgroup management operations added

 - kernfs and cgroup path formatting functions updated to behave in the
   style of strlcpy()

 - non-critical bug fixes

* 'for-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  blkcg: Unlock blkcg_pol_mutex only once when cpd == NULL
  cgroup: fix error handling regressions in proc_cgroup_show() and cgroup_release_agent()
  cpuset: fix error handling regression in proc_cpuset_show()
  cgroup: add tracepoints for basic operations
  cgroup: make cgroup_path() and friends behave in the style of strlcpy()
  kernfs: remove kernfs_path_len()
  kernfs: make kernfs_path*() behave in the style of strlcpy()
  kernfs: add dummy implementation of kernfs_path_from_node()

sysfs print name of undiscoverable attribute group

2016-09-27T10:24:29+00:00

Print the name of an undiscoverable attribute group and not the
pointer's address.

Signed-off-by: Johannes Thumshirn 
Signed-off-by: Greg Kroah-Hartman

sysfs: correctly handle read offset on PREALLOC attrs

2016-08-31T13:14:44+00:00

Attributes declared with __ATTR_PREALLOC use sysfs_kf_read() which returns
zero bytes for non-zero offset. This breaks script checkarray in mdadm tool
in debian where /bin/sh is 'dash' because its builtin 'read' reads only one
byte at a time. Script gets 'i' instead of 'idle' when reads current action
from /sys/block/$dev/md/sync_action and as a result does nothing.

This patch adds trivial implementation of partial read: generate whole
string and move required part into buffer head.

Signed-off-by: Konstantin Khlebnikov 
Fixes: 4ef67a8c95f3 ("sysfs/kernfs: make read requests on pre-alloc files use the buffer.")
Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=787950
Cc: Stable  # v3.19+
Acked-by: Tejun Heo 
Signed-off-by: Greg Kroah-Hartman