Commit 93b7e897 authored by Al Viro's avatar Al Viro Committed by Jinjiang Tu
Browse files

memcg_write_event_control(): fix a user-triggerable oops 

stable inclusion
from stable-v4.19.321
commit fa5bfdf6cb5846a00e712d630a43e3cf55ccb411
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAQOJK
CVE: CVE-2024-45021

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fa5bfdf6cb5846a00e712d630a43e3cf55ccb411



--------------------------------

commit 046667c4d3196938e992fba0dfcde570aa85cd0e upstream.

we are *not* guaranteed that anything past the terminating NUL
is mapped (let alone initialized with anything sane).

Fixes: 0dea1168 ("cgroup: implement eventfd-based generic API for notifications")
Cc: stable@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarJinjiang Tu <tujinjiang@huawei.com>
parent 4c94bdfb

mm/memcontrol.c

+5 −2
Original line number Diff line number Diff line
@@ -4578,9 +4578,12 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of, 
	buf = endp + 1;



	cfd = simple_strtoul(buf, &endp, 10);

	if ((*endp != ' ') && (*endp != '\0'))

		return -EINVAL;

	if (*endp == '\0')

		buf = endp;

	else if (*endp == ' ')

		buf = endp + 1;

	else

		return -EINVAL;



	event = kzalloc(sizeof(*event), GFP_KERNEL);

	if (!event)