Tejun Heo aad8bbd17a memcg: fix possible use-after-free in memcg_write_event_control() ... commit 4a7ba45b1a upstream. memcg_write_event_control() accesses the dentry->d_name of the specified control fd to route the write call. As a cgroup interface file can't be renamed, it's safe to access d_name as long as the specified file is a regular cgroup file. Also, as these cgroup interface files can't be removed before the directory, it's safe to access the parent too. Prior to 347c4a8747 ("memcg: remove cgroup_event->cft"), there was a call to __file_cft() which verified that the specified file is a regular cgroupfs file before further accesses. The cftype pointer returned from __file_cft() was no longer necessary and the commit inadvertently dropped the file type check with it allowing any file to slip through. With the invarients broken, the d_name and parent accesses can now race against renames and removals of arbitrary files and cause use-after-free's. Fix the bug by resurrecting the file type check in __file_cft(). Now that cgroupfs is implemented through kernfs, checking the file operations needs to go through a layer of indirection. Instead, let's check the superblock and dentry type. Link: https://lkml.kernel.org/r/Y5FRm/cfcKPGzWwl@slm.duckdns.org Fixes: 347c4a8747 ("memcg: remove cgroup_event->cft") Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jann Horn <jannh@google.com> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: <stable@vger.kernel.org> [3.14+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2022-12-14 11:37:19 +01:00
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acpi	ACPI: APEI: Fix integer overflow in ghes_estatus_pool_init()	2022-11-10 18:15:34 +01:00
asm-generic	mm/khugepaged: fix GUP-fast interaction by sending IPI	2022-12-14 11:37:17 +01:00
clocksource
crypto
drm	drm/bridge: Add stubs for devm_drm_of_get_bridge when OF is disabled	2022-09-05 10:30:03 +02:00
dt-bindings
keys
kunit
kvm
linux	memcg: fix possible use-after-free in memcg_write_event_control()	2022-12-14 11:37:19 +01:00
math-emu
media	media: v4l: subdev: Fail graciously when getting try data for NULL state	2022-11-10 18:15:34 +01:00
memory
misc
net	sctp: fix memory leak in sctp_stream_outq_migrate()	2022-12-08 11:28:41 +01:00
pcmcia
ras
rdma
scsi	scsi: iscsi: Add recv workqueue helpers	2022-10-26 12:35:15 +02:00
soc	ARM: at91: pm: avoid soft resetting AC DLL	2022-11-26 09:24:34 +01:00
sound	ALSA: control: Use deferred fasync helper	2022-08-25 11:40:44 +02:00
target
trace	rxrpc: Use refcount_t rather than atomic_t	2022-12-02 17:41:04 +01:00
uapi	audit: fix undefined behavior in bit shift for AUDIT_BIT	2022-12-02 17:41:01 +01:00
vdso
video
xen