4.20-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit ee74d0bd4325efb41e38affe5955f920ed973f23 ]
In case x25_connect() fails and frees the socket neighbour, we also need to undo the change done to x25->state.
Before my last bug fix, we had use-after-free so this patch fixes a latent bug.
syzbot report :
kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 16137 Comm: syz-executor.1 Not tainted 5.0.0+ #117 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:x25_write_internal+0x1e8/0xdf0 net/x25/x25_subr.c:173 Code: 00 40 88 b5 e0 fe ff ff 0f 85 01 0b 00 00 48 8b 8b 80 04 00 00 48 ba 00 00 00 00 00 fc ff df 48 8d 79 1c 48 89 fe 48 c1 ee 03 <0f> b6 34 16 48 89 fa 83 e2 07 83 c2 03 40 38 f2 7c 09 40 84 f6 0f RSP: 0018:ffff888076717a08 EFLAGS: 00010207 RAX: ffff88805f2f2292 RBX: ffff8880a0ae6000 RCX: 0000000000000000 kobject: 'loop5' (0000000018d0d0ee): kobject_uevent_env RDX: dffffc0000000000 RSI: 0000000000000003 RDI: 000000000000001c RBP: ffff888076717b40 R08: ffff8880950e0580 R09: ffffed100be5e46d R10: ffffed100be5e46c R11: ffff88805f2f2363 R12: ffff888065579840 kobject: 'loop5' (0000000018d0d0ee): fill_kobj_path: path = '/devices/virtual/block/loop5' R13: 1ffff1100ece2f47 R14: 0000000000000013 R15: 0000000000000013 FS: 00007fb88cf43700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9a42a41028 CR3: 0000000087a67000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: x25_release+0xd0/0x340 net/x25/af_x25.c:658 __sock_release+0xd3/0x2b0 net/socket.c:579 sock_close+0x1b/0x30 net/socket.c:1162 __fput+0x2df/0x8d0 fs/file_table.c:278 ____fput+0x16/0x20 fs/file_table.c:309 task_work_run+0x14a/0x1c0 kernel/task_work.c:113 get_signal+0x1961/0x1d50 kernel/signal.c:2388 do_signal+0x87/0x1940 arch/x86/kernel/signal.c:816 exit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x52d/0x610 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457f29 Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fb88cf42c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a RAX: fffffffffffffe00 RBX: 0000000000000003 RCX: 0000000000457f29 RDX: 0000000000000012 RSI: 0000000020000080 RDI: 0000000000000004 RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb88cf436d4 R13: 00000000004be462 R14: 00000000004cec98 R15: 00000000ffffffff Modules linked in:
Fixes: 95d6ebd53c79 ("net/x25: fix use-after-free in x25_device_event()") Signed-off-by: Eric Dumazet edumazet@google.com Cc: andrew hendry andrew.hendry@gmail.com Reported-by: syzbot syzkaller@googlegroups.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/x25/af_x25.c | 1 + 1 file changed, 1 insertion(+)
--- a/net/x25/af_x25.c +++ b/net/x25/af_x25.c @@ -822,6 +822,7 @@ out_put_neigh: x25_neigh_put(x25->neighbour); x25->neighbour = NULL; read_unlock_bh(&x25_list_lock); + x25->state = X25_STATE_0; } out_put_route: x25_route_put(rt);