| Message ID | 20240401211003.25274-1-kuniyu@amazon.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | d21d40605bca7bd5fc23ef03d4c1ca1f48bc2cae |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v2,net] ipv6: Fix infinite recursion in fib6_dump_done(). | expand |
On Mon, Apr 1, 2024 at 11:10 PM Kuniyuki Iwashima <kuniyu@amazon.com> wrote: > > syzkaller reported infinite recursive calls of fib6_dump_done() during > netlink socket destruction. [1] > > From the log, syzkaller sent an AF_UNSPEC RTM_GETROUTE message, and then > the response was generated. The following recvmmsg() resumed the dump > for IPv6, but the first call of inet6_dump_fib() failed at kzalloc() due > to the fault injection. [0] > > 12:01:34 executing program 3: > r0 = socket$nl_route(0x10, 0x3, 0x0) > sendmsg$nl_route(r0, ... snip ...) > recvmmsg(r0, ... snip ...) (fail_nth: 8) > > Here, fib6_dump_done() was set to nlk_sk(sk)->cb.done, and the next call > of inet6_dump_fib() set it to nlk_sk(sk)->cb.args[3]. syzkaller stopped > receiving the response halfway through, and finally netlink_sock_destruct() > called nlk_sk(sk)->cb.done(). It was not clear to me why we call inet6_dump_fib() a second time after the first call returned -ENOMEM It seems to be caused by rtnl_dump_all(), if the skb had info from IPv4 (skb->len != 0) "ip -6 ro" alone is not triggering the bug. > > fib6_dump_done() calls fib6_dump_end() and nlk_sk(sk)->cb.done() if it > is still not NULL. fib6_dump_end() rewrites nlk_sk(sk)->cb.done() by > nlk_sk(sk)->cb.args[3], but it has the same function, not NULL, calling > itself recursively and hitting the stack guard page. > > To avoid the issue, let's set the destructor after kzalloc(). > > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > Reported-by: syzkaller <syzkaller@googlegroups.com> > Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Reviewed-by: Eric Dumazet <edumazet@google.com>
On 4/1/24 3:10 PM, Kuniyuki Iwashima wrote: > syzkaller reported infinite recursive calls of fib6_dump_done() during > netlink socket destruction. [1] > > From the log, syzkaller sent an AF_UNSPEC RTM_GETROUTE message, and then > the response was generated. The following recvmmsg() resumed the dump > for IPv6, but the first call of inet6_dump_fib() failed at kzalloc() due > to the fault injection. [0] > > 12:01:34 executing program 3: > r0 = socket$nl_route(0x10, 0x3, 0x0) > sendmsg$nl_route(r0, ... snip ...) > recvmmsg(r0, ... snip ...) (fail_nth: 8) > > Here, fib6_dump_done() was set to nlk_sk(sk)->cb.done, and the next call > of inet6_dump_fib() set it to nlk_sk(sk)->cb.args[3]. syzkaller stopped > receiving the response halfway through, and finally netlink_sock_destruct() > called nlk_sk(sk)->cb.done(). > > fib6_dump_done() calls fib6_dump_end() and nlk_sk(sk)->cb.done() if it > is still not NULL. fib6_dump_end() rewrites nlk_sk(sk)->cb.done() by > nlk_sk(sk)->cb.args[3], but it has the same function, not NULL, calling > itself recursively and hitting the stack guard page. > > To avoid the issue, let's set the destructor after kzalloc(). > ... > Modules linked in: > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > Reported-by: syzkaller <syzkaller@googlegroups.com> > Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> > --- > Conflict with: > https://lore.kernel.org/netdev/20240329183053.644630-1-edumazet@google.com/ > > Changes: > v2: Removed the garbage in the head of description > v1: https://lore.kernel.org/netdev/20240401205020.22723-1-kuniyu@amazon.com/ > --- > net/ipv6/ip6_fib.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > Reviewed-by: David Ahern <dsahern@kernel.org>
Hello: This patch was applied to netdev/net.git (main) by Jakub Kicinski <kuba@kernel.org>: On Mon, 1 Apr 2024 14:10:04 -0700 you wrote: > syzkaller reported infinite recursive calls of fib6_dump_done() during > netlink socket destruction. [1] > > From the log, syzkaller sent an AF_UNSPEC RTM_GETROUTE message, and then > the response was generated. The following recvmmsg() resumed the dump > for IPv6, but the first call of inet6_dump_fib() failed at kzalloc() due > to the fault injection. [0] > > [...] Here is the summary with links: - [v2,net] ipv6: Fix infinite recursion in fib6_dump_done(). https://git.kernel.org/netdev/net/c/d21d40605bca You are awesome, thank you!
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index 5c558dc1c683..7209419cfb0e 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -651,19 +651,19 @@ static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) if (!w) { /* New dump: * - * 1. hook callback destructor. - */ - cb->args[3] = (long)cb->done; - cb->done = fib6_dump_done; - - /* - * 2. allocate and initialize walker. + * 1. allocate and initialize walker. */ w = kzalloc(sizeof(*w), GFP_ATOMIC); if (!w) return -ENOMEM; w->func = fib6_dump_node; cb->args[2] = (long)w; + + /* 2. hook callback destructor. + */ + cb->args[3] = (long)cb->done; + cb->done = fib6_dump_done; + } arg.skb = skb;
syzkaller reported infinite recursive calls of fib6_dump_done() during netlink socket destruction. [1] From the log, syzkaller sent an AF_UNSPEC RTM_GETROUTE message, and then the response was generated. The following recvmmsg() resumed the dump for IPv6, but the first call of inet6_dump_fib() failed at kzalloc() due to the fault injection. [0] 12:01:34 executing program 3: r0 = socket$nl_route(0x10, 0x3, 0x0) sendmsg$nl_route(r0, ... snip ...) recvmmsg(r0, ... snip ...) (fail_nth: 8) Here, fib6_dump_done() was set to nlk_sk(sk)->cb.done, and the next call of inet6_dump_fib() set it to nlk_sk(sk)->cb.args[3]. syzkaller stopped receiving the response halfway through, and finally netlink_sock_destruct() called nlk_sk(sk)->cb.done(). fib6_dump_done() calls fib6_dump_end() and nlk_sk(sk)->cb.done() if it is still not NULL. fib6_dump_end() rewrites nlk_sk(sk)->cb.done() by nlk_sk(sk)->cb.args[3], but it has the same function, not NULL, calling itself recursively and hitting the stack guard page. To avoid the issue, let's set the destructor after kzalloc(). [0]: FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 CPU: 1 PID: 432110 Comm: syz-executor.3 Not tainted 6.8.0-12821-g537c2e91d354-dirty #11 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 Call Trace: <TASK> dump_stack_lvl (lib/dump_stack.c:117) should_fail_ex (lib/fault-inject.c:52 lib/fault-inject.c:153) should_failslab (mm/slub.c:3733) kmalloc_trace (mm/slub.c:3748 mm/slub.c:3827 mm/slub.c:3992) inet6_dump_fib (./include/linux/slab.h:628 ./include/linux/slab.h:749 net/ipv6/ip6_fib.c:662) rtnl_dump_all (net/core/rtnetlink.c:4029) netlink_dump (net/netlink/af_netlink.c:2269) netlink_recvmsg (net/netlink/af_netlink.c:1988) ____sys_recvmsg (net/socket.c:1046 net/socket.c:2801) ___sys_recvmsg (net/socket.c:2846) do_recvmmsg (net/socket.c:2943) __x64_sys_recvmmsg (net/socket.c:3041 net/socket.c:3034 net/socket.c:3034) [1]: BUG: TASK stack guard page was hit at 00000000f2fa9af1 (stack is 00000000b7912430..000000009a436beb) stack guard page: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 223719 Comm: kworker/1:3 Not tainted 6.8.0-12821-g537c2e91d354-dirty #11 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 Workqueue: events netlink_sock_destruct_work RIP: 0010:fib6_dump_done (net/ipv6/ip6_fib.c:570) Code: 3c 24 e8 f3 e9 51 fd e9 28 fd ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 41 57 41 56 41 55 41 54 55 48 89 fd <53> 48 8d 5d 60 e8 b6 4d 07 fd 48 89 da 48 b8 00 00 00 00 00 fc ff RSP: 0018:ffffc9000d980000 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffffffff84405990 RCX: ffffffff844059d3 RDX: ffff8881028e0000 RSI: ffffffff84405ac2 RDI: ffff88810c02f358 RBP: ffff88810c02f358 R08: 0000000000000007 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000224 R12: 0000000000000000 R13: ffff888007c82c78 R14: ffff888007c82c68 R15: ffff888007c82c68 FS: 0000000000000000(0000) GS:ffff88811b100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffc9000d97fff8 CR3: 0000000102309002 CR4: 0000000000770ef0 PKRU: 55555554 Call Trace: <#DF> </#DF> <TASK> fib6_dump_done (net/ipv6/ip6_fib.c:572 (discriminator 1)) fib6_dump_done (net/ipv6/ip6_fib.c:572 (discriminator 1)) ... fib6_dump_done (net/ipv6/ip6_fib.c:572 (discriminator 1)) fib6_dump_done (net/ipv6/ip6_fib.c:572 (discriminator 1)) netlink_sock_destruct (net/netlink/af_netlink.c:401) __sk_destruct (net/core/sock.c:2177 (discriminator 2)) sk_destruct (net/core/sock.c:2224) __sk_free (net/core/sock.c:2235) sk_free (net/core/sock.c:2246) process_one_work (kernel/workqueue.c:3259) worker_thread (kernel/workqueue.c:3329 kernel/workqueue.c:3416) kthread (kernel/kthread.c:388) ret_from_fork (arch/x86/kernel/process.c:153) ret_from_fork_asm (arch/x86/entry/entry_64.S:256) Modules linked in: Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzkaller <syzkaller@googlegroups.com> Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> --- Conflict with: https://lore.kernel.org/netdev/20240329183053.644630-1-edumazet@google.com/ Changes: v2: Removed the garbage in the head of description v1: https://lore.kernel.org/netdev/20240401205020.22723-1-kuniyu@amazon.com/ --- net/ipv6/ip6_fib.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)