On Thu, 21 Mar 2019 09:32:42 -0400 Steven Rostedt <rost...@goodmis.org> wrote:
> I tested your code and it also fixes the issue, Although I just hit this: ------------[ cut here ]------------ General protection fault in user access. Non-canonical address? WARNING: CPU: 2 PID: 1620 at arch/x86/mm/extable.c:125 ex_handler_uaccess+0xc4/0xf0 Modules linked in: iptable_mangle xt_CHECKSUM tun bridge stp llc ebtable_filter ebtables ip6table_filter ip6_tables ipt_REJECT nf_reject_ipv4 xt_tcpudp xt_state xt_conntrack nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 iptable_filter snd_hda_codec_hdmi iTCO_wdt snd_hda_codec_realtek snd_hda_codec_generic iTCO_vendor_support wmi_bmof snd_hda_intel snd_hda_codec intel_rapl x86_pkg_temp_thermal intel_powerclamp snd_hda_core coretemp snd_seq crct10dif_pclmul crct10dif_common i915 aesni_intel snd_seq_device snd_pcm aes_x86_64 crypto_simd cryptd snd_timer glue_helper i2c_i801 lpc_ich video wmi pcc_cpufreq ip_tables x_tables e1000e CPU: 2 PID: 1620 Comm: dhclient Not tainted 5.1.0-rc1-test-yocto-standard+ #42 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v03.03 07/14/2016 RIP: 0010:ex_handler_uaccess+0xc4/0xf0 Code: 01 00 00 00 31 d2 be 01 00 00 00 48 c7 c7 e8 ca f6 ac c6 05 23 9f 8e 01 01 e8 68 df 11 00 48 c7 c7 20 69 b9 ac e8 4b 42 01 00 <0f> 0b b9 01 00 00 00 31 d2 be 01 00 00 00 48 c7 c7 b8 ca f6 ac e8 RSP: 0018:ffffa4bd409e79a0 EFLAGS: 00010086 RAX: 0000000000000000 RBX: ffffffffac602400 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffacf7f118 RBP: ffffa4bd409e79b8 R08: ffffffffad27ba00 R09: 000000000000003f R10: 0000000000000000 R11: 0000000000000654 R12: 0000000000000001 R13: ffffa4bd409e7a28 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f7e2fe13e80(0000) GS:ffff8b101a880000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000001010 CR3: 0000000114d68001 CR4: 00000000001606e0 Call Trace: fixup_exception+0x4a/0x61 do_general_protection+0x50/0x190 general_protection+0x27/0x30 RIP: 0010:save_stack_trace_user+0xc9/0x190 Code: 0f 96 c6 48 c7 c7 88 6a f6 ac 31 c9 e8 40 e8 14 00 49 39 dc 0f 87 c3 00 00 00 41 83 87 a0 18 00 00 01 0f 1f 00 0f ae e8 31 db <4d> 8b 3c 24 31 f6 85 db ba 01 00 00 00 40 0f 94 c6 48 c7 c7 b8 6a RSP: 0018:ffffa4bd409e7ad8 EFLAGS: 00010046 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000001 RSI: 0000000000000001 RDI: ffffffffacf66a88 RBP: ffffa4bd409e7b00 R08: 0000000000000000 R09: ffff8b0fb4df1a08 R10: 00000000000009f4 R11: ffff8b0fb4df1a04 R12: 62696c2f7273752f R13: ffffa4bd409e7f58 R14: ffffa4bd409e7b10 R15: ffff8b1017d53a80 ? save_stack_trace_user+0xb0/0x190 ftrace_trace_userstack+0x128/0x1c0 trace_buffer_unlock_commit_regs+0x83/0xb0 trace_event_buffer_commit+0x6e/0x1e0 trace_event_raw_event_preemptirq_template+0x73/0xb0 ? __get_user_pages+0x2d0/0x860 ? handle_mm_fault+0xa9/0x3c0 trace_hardirqs_off+0xbd/0x100 handle_mm_fault+0xa9/0x3c0 __get_user_pages+0x2d0/0x860 get_user_pages_remote+0x169/0x260 copy_strings.isra.8.part.9+0x18e/0x300 copy_strings_kernel+0x39/0x50 __do_execve_file.isra.14+0x5b3/0x9e0 do_execve+0x25/0x30 __x64_sys_execve+0x2b/0x40 do_syscall_64+0x79/0x1f0 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f7e30272b0b Code: 41 89 01 eb da 66 2e 0f 1f 84 00 00 00 00 00 f7 d8 64 41 89 01 eb d6 0f 1f 84 00 00 00 00 00 f3 0f 1e fa b8 3b 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 4d 63 0f 00 f7 d8 64 89 01 48 RSP: 002b:00007ffc34858f28 EFLAGS: 00000206 ORIG_RAX: 000000000000003b RAX: ffffffffffffffda RBX: 00005635d0651f60 RCX: 00007f7e30272b0b RDX: 00005635d0658a60 RSI: 00007ffc34858f40 RDI: 00007ffc3485ae89 RBP: 00007ffc3485ae89 R08: 00005635d05ff290 R09: 0000000000000001 R10: 00007f7e2fe13e80 R11: 0000000000000206 R12: 00005635d0658a60 R13: 0000000000000000 R14: 00005635d05d9be0 R15: 0000000000000136 ---[ end trace 0a02ebd5916dacc5 ]--- Looks to be an issue with the save_stack_trace_user() not checking if the address is canonical before reading it. I guess access_ok() doesn't check that. Should we add something in save_stack_trace_user() to test if the frame it reads is canonical or not before reading it. We don't really want these warnings to happen because the user space stack has a non-canonical address in it as the stack tracer reads it. --- Steve
