| Message ID | c31f454f74833b2003713fffa881aabb190b8290.1656031586.git.duoming@zju.edu.cn (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | Fix UAF and null-ptr-deref bugs in rose protocol | 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: 1 this patch: 1 |
| netdev/cc_maintainers | success | CCed 7 of 7 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/check_selftest | success | No net selftest shell script |
| netdev/verify_fixes | success | Fixes tag looks correct |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 1 this patch: 1 |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 24 lines checked |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/source_inline | success | Was 0 now: 0 |
On Fri, 2022-06-24 at 09:05 +0800, Duoming Zhou wrote: > When the link layer connection is broken, the rose->neighbour is > set to null. But rose->neighbour could be used by rose_connection() > and rose_release() later, because there is no synchronization among > them. As a result, the null-ptr-deref bugs will happen. > > One of the null-ptr-deref bugs is shown below: > > (thread 1) | (thread 2) > | rose_connect > rose_kill_by_neigh | lock_sock(sk) > spin_lock_bh(&rose_list_lock) | if (!rose->neighbour) > rose->neighbour = NULL;//(1) | > | rose->neighbour->use++;//(2) > > The rose->neighbour is set to null in position (1) and dereferenced > in position (2). > > The KASAN report triggered by POC is shown below: > > KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f] > ... > RIP: 0010:rose_connect+0x6c2/0xf30 > RSP: 0018:ffff88800ab47d60 EFLAGS: 00000206 > RAX: 0000000000000005 RBX: 000000000000002a RCX: 0000000000000000 > RDX: ffff88800ab38000 RSI: ffff88800ab47e48 RDI: ffff88800ab38309 > RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffed1001567062 > R10: dfffe91001567063 R11: 1ffff11001567061 R12: 1ffff11000d17cd0 > R13: ffff8880068be680 R14: 0000000000000002 R15: 1ffff11000d17cd0 > ... > Call Trace: > <TASK> > ? __local_bh_enable_ip+0x54/0x80 > ? selinux_netlbl_socket_connect+0x26/0x30 > ? rose_bind+0x5b0/0x5b0 > __sys_connect+0x216/0x280 > __x64_sys_connect+0x71/0x80 > do_syscall_64+0x43/0x90 > entry_SYSCALL_64_after_hwframe+0x46/0xb0 > > This patch adds lock_sock() in rose_kill_by_neigh() in order to > synchronize with rose_connect() and rose_release(). > > Meanwhile, this patch adds sock_hold() protected by rose_list_lock > that could synchronize with rose_remove_socket() in order to mitigate > UAF bug caused by lock_sock() we add. > > What's more, there is no need using rose_neigh_list_lock to protect > rose_kill_by_neigh(). Because we have already used rose_neigh_list_lock > to protect the state change of rose_neigh in rose_link_failed(), which > is well synchronized. > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> > --- > Changes since v2: > - v2: Fix refcount leak of sock. > > net/rose/af_rose.c | 6 ++++++ > net/rose/rose_route.c | 2 ++ > 2 files changed, 8 insertions(+) > > diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c > index bf2d986a6bc..5caa222c490 100644 > --- a/net/rose/af_rose.c > +++ b/net/rose/af_rose.c > @@ -169,9 +169,15 @@ void rose_kill_by_neigh(struct rose_neigh *neigh) > struct rose_sock *rose = rose_sk(s); > > if (rose->neighbour == neigh) { > + sock_hold(s); > rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0); > rose->neighbour->use--; > + spin_unlock_bh(&rose_list_lock); > + lock_sock(s); > rose->neighbour = NULL; > + release_sock(s); > + spin_lock_bh(&rose_list_lock); I'm sorry, I likely was not clear enough in my previous reply. This is broken. If a list is [spin_]lock protected, you can't release the lock, reacquire it and continue traversing the list from the [now invalid] same iterator. e.g. if s is removed from the list, even if the sock is not de- allocated due to the addtional refcount, the traversing will errnously stop after this sock, instead of continuing processing the remaining socks in the list. A possible alternative, not even build-tested would be: --- diff --git a/include/net/rose.h b/include/net/rose.h index 0f0a4ce0fee7..090db11d528f 100644 --- a/include/net/rose.h +++ b/include/net/rose.h @@ -145,6 +145,7 @@ struct rose_sock { struct rose_facilities_struct facilities; struct timer_list timer; struct timer_list idletimer; + struct rose_sock *dl_next; }; #define rose_sk(sk) ((struct rose_sock *)(sk)) diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c index 5caa222c490e..01f3c50f0921 100644 --- a/net/rose/af_rose.c +++ b/net/rose/af_rose.c @@ -162,25 +162,32 @@ static void rose_remove_socket(struct sock *sk) */ void rose_kill_by_neigh(struct rose_neigh *neigh) { - struct sock *s; + struct rose_sock *del_list = NULL; + struct sock *s, *tmp; spin_lock_bh(&rose_list_lock); - sk_for_each(s, &rose_list) { + sk_for_each_safe(s, tmp, &rose_list) { struct rose_sock *rose = rose_sk(s); if (rose->neighbour == neigh) { - sock_hold(s); - rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0); - rose->neighbour->use--; - spin_unlock_bh(&rose_list_lock); - lock_sock(s); - rose->neighbour = NULL; - release_sock(s); - spin_lock_bh(&rose_list_lock); - sock_put(s); + __sk_del_node(s); + s->dl_next = del_list; + del_list = s; } } spin_unlock_bh(&rose_list_lock); + + while (del_list) { + s = del_list; + del_list = s->dl_next; + + lock_sock(s); + rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0); + rose->neighbour->use--; + rose->neighbour = NULL; + release_sock(s); + sock_put(s); + } } /* --- Paolo
Hello, On Tue, 28 Jun 2022 13:12:40 +0200 Paolo Abeni wrote: > > When the link layer connection is broken, the rose->neighbour is > > set to null. But rose->neighbour could be used by rose_connection() > > and rose_release() later, because there is no synchronization among > > them. As a result, the null-ptr-deref bugs will happen. > > > > One of the null-ptr-deref bugs is shown below: > > > > (thread 1) | (thread 2) > > | rose_connect > > rose_kill_by_neigh | lock_sock(sk) > > spin_lock_bh(&rose_list_lock) | if (!rose->neighbour) > > rose->neighbour = NULL;//(1) | > > | rose->neighbour->use++;//(2) > > > > The rose->neighbour is set to null in position (1) and dereferenced > > in position (2). > > > > The KASAN report triggered by POC is shown below: > > > > KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f] > > ... > > RIP: 0010:rose_connect+0x6c2/0xf30 > > RSP: 0018:ffff88800ab47d60 EFLAGS: 00000206 > > RAX: 0000000000000005 RBX: 000000000000002a RCX: 0000000000000000 > > RDX: ffff88800ab38000 RSI: ffff88800ab47e48 RDI: ffff88800ab38309 > > RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffed1001567062 > > R10: dfffe91001567063 R11: 1ffff11001567061 R12: 1ffff11000d17cd0 > > R13: ffff8880068be680 R14: 0000000000000002 R15: 1ffff11000d17cd0 > > ... > > Call Trace: > > <TASK> > > ? __local_bh_enable_ip+0x54/0x80 > > ? selinux_netlbl_socket_connect+0x26/0x30 > > ? rose_bind+0x5b0/0x5b0 > > __sys_connect+0x216/0x280 > > __x64_sys_connect+0x71/0x80 > > do_syscall_64+0x43/0x90 > > entry_SYSCALL_64_after_hwframe+0x46/0xb0 > > > > This patch adds lock_sock() in rose_kill_by_neigh() in order to > > synchronize with rose_connect() and rose_release(). > > > > Meanwhile, this patch adds sock_hold() protected by rose_list_lock > > that could synchronize with rose_remove_socket() in order to mitigate > > UAF bug caused by lock_sock() we add. > > > > What's more, there is no need using rose_neigh_list_lock to protect > > rose_kill_by_neigh(). Because we have already used rose_neigh_list_lock > > to protect the state change of rose_neigh in rose_link_failed(), which > > is well synchronized. > > > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > > Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> > > --- > > Changes since v2: > > - v2: Fix refcount leak of sock. > > > > net/rose/af_rose.c | 6 ++++++ > > net/rose/rose_route.c | 2 ++ > > 2 files changed, 8 insertions(+) > > > > diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c > > index bf2d986a6bc..5caa222c490 100644 > > --- a/net/rose/af_rose.c > > +++ b/net/rose/af_rose.c > > @@ -169,9 +169,15 @@ void rose_kill_by_neigh(struct rose_neigh *neigh) > > struct rose_sock *rose = rose_sk(s); > > > > if (rose->neighbour == neigh) { > > + sock_hold(s); > > rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0); > > rose->neighbour->use--; > > + spin_unlock_bh(&rose_list_lock); > > + lock_sock(s); > > rose->neighbour = NULL; > > + release_sock(s); > > + spin_lock_bh(&rose_list_lock); > > I'm sorry, I likely was not clear enough in my previous reply. This is > broken. If a list is [spin_]lock protected, you can't release the lock, > reacquire it and continue traversing the list from the [now invalid] > same iterator. > > e.g. if s is removed from the list, even if the sock is not de- > allocated due to the addtional refcount, the traversing will errnously > stop after this sock, instead of continuing processing the remaining > socks in the list. I understand. The following is a new solution: diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c index bf2d986a6bc..24dcbde88fb 100644 --- a/net/rose/af_rose.c +++ b/net/rose/af_rose.c @@ -165,13 +165,21 @@ void rose_kill_by_neigh(struct rose_neigh *neigh) struct sock *s; spin_lock_bh(&rose_list_lock); +again: sk_for_each(s, &rose_list) { struct rose_sock *rose = rose_sk(s); if (rose->neighbour == neigh) { + sock_hold(s); + spin_unlock_bh(&rose_list_lock); + lock_sock(s); rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0); rose->neighbour->use--; rose->neighbour = NULL; + release_sock(s); + spin_lock_bh(&rose_list_lock); + sock_put(s); + goto again; } } spin_unlock_bh(&rose_list_lock); diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c index fee6409c2bb..b116828b422 100644 --- a/net/rose/rose_route.c +++ b/net/rose/rose_route.c @@ -827,7 +827,9 @@ void rose_link_failed(ax25_cb *ax25, int reason) ax25_cb_put(ax25); rose_del_route_by_neigh(rose_neigh); + spin_unlock_bh(&rose_neigh_list_lock); rose_kill_by_neigh(rose_neigh); + return; } spin_unlock_bh(&rose_neigh_list_lock); } If s is removed from the list, the traversing will not stop erroneously. Best regards, Duoming Zhou
On Tue, Jun 28, 2022 at 11:59 PM <duoming@zju.edu.cn> wrote: > Hello, > > On Tue, 28 Jun 2022 13:12:40 +0200 Paolo Abeni wrote: > > [snip] > > I'm sorry, I likely was not clear enough in my previous reply. This is > > broken. If a list is [spin_]lock protected, you can't release the lock, > > reacquire it and continue traversing the list from the [now invalid] > > same iterator. > > > > e.g. if s is removed from the list, even if the sock is not de- > > allocated due to the addtional refcount, the traversing will errnously > > stop after this sock, instead of continuing processing the remaining > > socks in the list. > > I understand. The following is a new solution: > > diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c > index bf2d986a6bc..24dcbde88fb 100644 > --- a/net/rose/af_rose.c > +++ b/net/rose/af_rose.c > @@ -165,13 +165,21 @@ void rose_kill_by_neigh(struct rose_neigh *neigh) > struct sock *s; > > spin_lock_bh(&rose_list_lock); > +again: > sk_for_each(s, &rose_list) { > struct rose_sock *rose = rose_sk(s); > > if (rose->neighbour == neigh) { > + sock_hold(s); > + spin_unlock_bh(&rose_list_lock); > + lock_sock(s); > rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0); > rose->neighbour->use--; > rose->neighbour = NULL; > + release_sock(s); > + spin_lock_bh(&rose_list_lock); > + sock_put(s); > + goto again; It may be worthwhile noting that this changes the time complexity of the algorithm to be O(n^2) in the number of entries in `rose_list`, instead of linear. But as that number is extremely unlikely to ever be large, it probably makes no practical difference. - Dan C. > } > } > spin_unlock_bh(&rose_list_lock); > diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c > index fee6409c2bb..b116828b422 100644 > --- a/net/rose/rose_route.c > +++ b/net/rose/rose_route.c > @@ -827,7 +827,9 @@ void rose_link_failed(ax25_cb *ax25, int reason) > ax25_cb_put(ax25); > > rose_del_route_by_neigh(rose_neigh); > + spin_unlock_bh(&rose_neigh_list_lock); > rose_kill_by_neigh(rose_neigh); > + return; > } > spin_unlock_bh(&rose_neigh_list_lock); > } > > If s is removed from the list, the traversing will not stop erroneously. > > Best regards, > Duoming Zhou
diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c index bf2d986a6bc..5caa222c490 100644 --- a/net/rose/af_rose.c +++ b/net/rose/af_rose.c @@ -169,9 +169,15 @@ void rose_kill_by_neigh(struct rose_neigh *neigh) struct rose_sock *rose = rose_sk(s); if (rose->neighbour == neigh) { + sock_hold(s); rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0); rose->neighbour->use--; + spin_unlock_bh(&rose_list_lock); + lock_sock(s); rose->neighbour = NULL; + release_sock(s); + spin_lock_bh(&rose_list_lock); + sock_put(s); } } spin_unlock_bh(&rose_list_lock); diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c index fee6409c2bb..b116828b422 100644 --- a/net/rose/rose_route.c +++ b/net/rose/rose_route.c @@ -827,7 +827,9 @@ void rose_link_failed(ax25_cb *ax25, int reason) ax25_cb_put(ax25); rose_del_route_by_neigh(rose_neigh); + spin_unlock_bh(&rose_neigh_list_lock); rose_kill_by_neigh(rose_neigh); + return; } spin_unlock_bh(&rose_neigh_list_lock); }
When the link layer connection is broken, the rose->neighbour is set to null. But rose->neighbour could be used by rose_connection() and rose_release() later, because there is no synchronization among them. As a result, the null-ptr-deref bugs will happen. One of the null-ptr-deref bugs is shown below: (thread 1) | (thread 2) | rose_connect rose_kill_by_neigh | lock_sock(sk) spin_lock_bh(&rose_list_lock) | if (!rose->neighbour) rose->neighbour = NULL;//(1) | | rose->neighbour->use++;//(2) The rose->neighbour is set to null in position (1) and dereferenced in position (2). The KASAN report triggered by POC is shown below: KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f] ... RIP: 0010:rose_connect+0x6c2/0xf30 RSP: 0018:ffff88800ab47d60 EFLAGS: 00000206 RAX: 0000000000000005 RBX: 000000000000002a RCX: 0000000000000000 RDX: ffff88800ab38000 RSI: ffff88800ab47e48 RDI: ffff88800ab38309 RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffed1001567062 R10: dfffe91001567063 R11: 1ffff11001567061 R12: 1ffff11000d17cd0 R13: ffff8880068be680 R14: 0000000000000002 R15: 1ffff11000d17cd0 ... Call Trace: <TASK> ? __local_bh_enable_ip+0x54/0x80 ? selinux_netlbl_socket_connect+0x26/0x30 ? rose_bind+0x5b0/0x5b0 __sys_connect+0x216/0x280 __x64_sys_connect+0x71/0x80 do_syscall_64+0x43/0x90 entry_SYSCALL_64_after_hwframe+0x46/0xb0 This patch adds lock_sock() in rose_kill_by_neigh() in order to synchronize with rose_connect() and rose_release(). Meanwhile, this patch adds sock_hold() protected by rose_list_lock that could synchronize with rose_remove_socket() in order to mitigate UAF bug caused by lock_sock() we add. What's more, there is no need using rose_neigh_list_lock to protect rose_kill_by_neigh(). Because we have already used rose_neigh_list_lock to protect the state change of rose_neigh in rose_link_failed(), which is well synchronized. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> --- Changes since v2: - v2: Fix refcount leak of sock. net/rose/af_rose.c | 6 ++++++ net/rose/rose_route.c | 2 ++ 2 files changed, 8 insertions(+)