Eric Biggers 5f5fb7cea8 Smack: fix use-after-free in smk_write_relabel_self() ... commit beb4ee6770 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2020-08-11 15:33:35 +02:00
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Kconfig	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
smack.h	smack: avoid unused 'sip' variable warning	2020-06-17 16:40:22 +02:00
smack_access.c	smack: use GFP_NOFS while holding inode_smack::smk_lock	2019-09-04 09:37:07 -07:00
smack_lsm.c	smack: avoid unused 'sip' variable warning	2020-06-17 16:40:22 +02:00
smack_netfilter.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500	2019-06-19 17:09:55 +02:00
smackfs.c	Smack: fix use-after-free in smk_write_relabel_self()	2020-08-11 15:33:35 +02:00