| Message ID | 3a6285cd55b196a16cdf19603b16951a18f8387b.1648472006.git.duoming@zju.edu.cn (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 5352a761308397a0e6250fdc629bb3f615b94747 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | Fix UAF bugs caused by ax25_release() | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Clearly marked for net |
| netdev/fixes_present | success | Fixes tag present in non-next series |
| netdev/subject_prefix | success | Link |
| netdev/cover_letter | success | Series has a cover letter |
| netdev/patch_count | success | Link |
| netdev/header_inline | success | No static functions without inline keyword in header files |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/cc_maintainers | success | CCed 8 of 8 maintainers |
| netdev/build_clang | success | Errors and warnings before: 0 this patch: 0 |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Signed-off-by tag matches author and committer |
| netdev/verify_fixes | success | Fixes tag looks correct |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 20 lines checked |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/source_inline | success | Was 0 now: 0 |
diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c index 992b6e5d85d..f5686c463bc 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -991,10 +991,6 @@ static int ax25_release(struct socket *sock) sock_orphan(sk); ax25 = sk_to_ax25(sk); ax25_dev = ax25->ax25_dev; - if (ax25_dev) { - dev_put_track(ax25_dev->dev, &ax25_dev->dev_tracker); - ax25_dev_put(ax25_dev); - } if (sk->sk_type == SOCK_SEQPACKET) { switch (ax25->state) { @@ -1056,6 +1052,10 @@ static int ax25_release(struct socket *sock) sk->sk_state_change(sk); ax25_destroy_socket(ax25); } + if (ax25_dev) { + dev_put_track(ax25_dev->dev, &ax25_dev->dev_tracker); + ax25_dev_put(ax25_dev); + } sock->sk = NULL; release_sock(sk);
There are UAF bugs in ax25_send_control(), when we call ax25_release() to deallocate ax25_dev. The possible race condition is shown below: (Thread 1) | (Thread 2) ax25_dev_device_up() //(1) | | ax25_kill_by_device() ax25_bind() //(2) | ax25_connect() | ... ax25->state = AX25_STATE_1 | ... | ax25_dev_device_down() //(3) (Thread 3) ax25_release() | ax25_dev_put() //(4) FREE | case AX25_STATE_1: | ax25_send_control() | alloc_skb() //USE | The refcount of ax25_dev increases in position (1) and (2), and decreases in position (3) and (4). The ax25_dev will be freed before dereference sites in ax25_send_control(). The following is part of the report: [ 102.297448] BUG: KASAN: use-after-free in ax25_send_control+0x33/0x210 [ 102.297448] Read of size 8 at addr ffff888009e6e408 by task ax25_close/602 [ 102.297448] Call Trace: [ 102.303751] ax25_send_control+0x33/0x210 [ 102.303751] ax25_release+0x356/0x450 [ 102.305431] __sock_release+0x6d/0x120 [ 102.305431] sock_close+0xf/0x20 [ 102.305431] __fput+0x11f/0x420 [ 102.305431] task_work_run+0x86/0xd0 [ 102.307130] get_signal+0x1075/0x1220 [ 102.308253] arch_do_signal_or_restart+0x1df/0xc00 [ 102.308253] exit_to_user_mode_prepare+0x150/0x1e0 [ 102.308253] syscall_exit_to_user_mode+0x19/0x50 [ 102.308253] do_syscall_64+0x48/0x90 [ 102.308253] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 102.308253] RIP: 0033:0x405ae7 This patch defers the free operation of ax25_dev and net_device after all corresponding dereference sites in ax25_release() to avoid UAF. Fixes: 9fd75b66b8f6 ("ax25: Fix refcount leaks caused by ax25_cb_del()") Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> --- Changes in V2: - Make commit message more clearer. net/ax25/af_ax25.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)