forked from TencentOS/TencentOS-kernel
bced6f0ceb
commit beb4ee6770a89646659e6a2178538d2b13e2654e 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: 38416e53936e ("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>
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|---|---|---|
| .. | ||
| apparmor | ||
| integrity | ||
| keys | ||
| loadpin | ||
| lockdown | ||
| safesetid | ||
| selinux | ||
| smack | ||
| tomoyo | ||
| yama | ||
| Kconfig | ||
| Kconfig.hardening | ||
| Makefile | ||
| commoncap.c | ||
| device_cgroup.c | ||
| inode.c | ||
| lsm_audit.c | ||
| min_addr.c | ||
| security.c | ||