linux/security
Eric Biggers beb4ee6770 Smack: fix use-after-free in smk_write_relabel_self()
smk_write_relabel_self() frees memory from the task's credentials with
no locking, which can easily cause a use-after-free because multiple
tasks can share the same credentials structure.

Fix this by using prepare_creds() and commit_creds() to correctly modify
the task's credentials.

Reproducer for "BUG: KASAN: use-after-free in smk_write_relabel_self":

	#include <fcntl.h>
	#include <pthread.h>
	#include <unistd.h>

	static void *thrproc(void *arg)
	{
		int fd = open("/sys/fs/smackfs/relabel-self", O_WRONLY);
		for (;;) write(fd, "foo", 3);
	}

	int main()
	{
		pthread_t t;
		pthread_create(&t, NULL, thrproc, NULL);
		thrproc(NULL);
	}

Reported-by: syzbot+e6416dabb497a650da40@syzkaller.appspotmail.com
Fixes: 38416e5393 ("Smack: limited capability for changing process label")
Cc: <stable@vger.kernel.org> # v4.4+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
2020-07-14 11:19:58 -07:00
..
apparmor linux-kselftest-kunit-5.8-rc1 2020-06-09 10:04:47 -07:00
bpf bpf: lsm: Initialize the BPF LSM hooks 2020-03-30 01:34:00 +02:00
integrity ima: mprotect performance fix 2020-06-12 12:02:41 -07:00
keys Notifications over pipes + Keyring notifications 2020-06-13 09:56:21 -07:00
loadpin proc/sysctl: add shared variables for range check 2019-07-18 17:08:07 -07:00
lockdown Merge branch 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2020-06-02 17:36:24 -07:00
safesetid security/safesetid: Replace rcu_swap_protected() with rcu_replace_pointer() 2019-10-30 08:45:57 -07:00
selinux Notifications over pipes + Keyring notifications 2020-06-13 09:56:21 -07:00
smack Smack: fix use-after-free in smk_write_relabel_self() 2020-07-14 11:19:58 -07:00
tomoyo treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
yama sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
commoncap.c exec: Compute file based creds only once 2020-05-29 22:00:54 -05:00
device_cgroup.c device_cgroup: Cleanup cgroup eBPF device filter code 2020-04-13 14:41:54 -04:00
inode.c Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
Kconfig bpf: lsm: Initialize the BPF LSM hooks 2020-03-30 01:34:00 +02:00
Kconfig.hardening meminit fix 2019-07-28 12:33:15 -07:00
lsm_audit.c security,lockdown,selinux: implement SELinux lockdown 2019-12-09 17:53:58 -05:00
Makefile device_cgroup: Cleanup cgroup eBPF device filter code 2020-04-13 14:41:54 -04:00
min_addr.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
security.c Add additional LSM hooks for SafeSetID 2020-06-14 11:39:31 -07:00