linux/kernel/trace
Josh Poimboeuf 9f255b632b module: Fix livepatch/ftrace module text permissions race
It's possible for livepatch and ftrace to be toggling a module's text
permissions at the same time, resulting in the following panic:

  BUG: unable to handle page fault for address: ffffffffc005b1d9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0003) - permissions violation
  PGD 3ea0c067 P4D 3ea0c067 PUD 3ea0e067 PMD 3cc13067 PTE 3b8a1061
  Oops: 0003 [#1] PREEMPT SMP PTI
  CPU: 1 PID: 453 Comm: insmod Tainted: G           O  K   5.2.0-rc1-a188339ca5 #1
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-20181126_142135-anatol 04/01/2014
  RIP: 0010:apply_relocate_add+0xbe/0x14c
  Code: fa 0b 74 21 48 83 fa 18 74 38 48 83 fa 0a 75 40 eb 08 48 83 38 00 74 33 eb 53 83 38 00 75 4e 89 08 89 c8 eb 0a 83 38 00 75 43 <89> 08 48 63 c1 48 39 c8 74 2e eb 48 83 38 00 75 32 48 29 c1 89 08
  RSP: 0018:ffffb223c00dbb10 EFLAGS: 00010246
  RAX: ffffffffc005b1d9 RBX: 0000000000000000 RCX: ffffffff8b200060
  RDX: 000000000000000b RSI: 0000004b0000000b RDI: ffff96bdfcd33000
  RBP: ffffb223c00dbb38 R08: ffffffffc005d040 R09: ffffffffc005c1f0
  R10: ffff96bdfcd33c40 R11: ffff96bdfcd33b80 R12: 0000000000000018
  R13: ffffffffc005c1f0 R14: ffffffffc005e708 R15: ffffffff8b2fbc74
  FS:  00007f5f447beba8(0000) GS:ffff96bdff900000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: ffffffffc005b1d9 CR3: 000000003cedc002 CR4: 0000000000360ea0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   klp_init_object_loaded+0x10f/0x219
   ? preempt_latency_start+0x21/0x57
   klp_enable_patch+0x662/0x809
   ? virt_to_head_page+0x3a/0x3c
   ? kfree+0x8c/0x126
   patch_init+0x2ed/0x1000 [livepatch_test02]
   ? 0xffffffffc0060000
   do_one_initcall+0x9f/0x1c5
   ? kmem_cache_alloc_trace+0xc4/0xd4
   ? do_init_module+0x27/0x210
   do_init_module+0x5f/0x210
   load_module+0x1c41/0x2290
   ? fsnotify_path+0x3b/0x42
   ? strstarts+0x2b/0x2b
   ? kernel_read+0x58/0x65
   __do_sys_finit_module+0x9f/0xc3
   ? __do_sys_finit_module+0x9f/0xc3
   __x64_sys_finit_module+0x1a/0x1c
   do_syscall_64+0x52/0x61
   entry_SYSCALL_64_after_hwframe+0x44/0xa9

The above panic occurs when loading two modules at the same time with
ftrace enabled, where at least one of the modules is a livepatch module:

CPU0					CPU1
klp_enable_patch()
  klp_init_object_loaded()
    module_disable_ro()
    					ftrace_module_enable()
					  ftrace_arch_code_modify_post_process()
				    	    set_all_modules_text_ro()
      klp_write_object_relocations()
        apply_relocate_add()
	  *patches read-only code* - BOOM

A similar race exists when toggling ftrace while loading a livepatch
module.

Fix it by ensuring that the livepatch and ftrace code patching
operations -- and their respective permissions changes -- are protected
by the text_mutex.

Link: http://lkml.kernel.org/r/ab43d56ab909469ac5d2520c5d944ad6d4abd476.1560474114.git.jpoimboe@redhat.com

Reported-by: Johannes Erdfelt <johannes@erdfelt.com>
Fixes: 444d13ff10 ("modules: add ro_after_init support")
Acked-by: Jessica Yu <jeyu@kernel.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-06-14 17:01:50 -04:00
..
blktrace.c blkcg: annotate implicit fall through 2019-03-13 14:31:12 -06:00
bpf_trace.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2019-05-07 22:03:58 -07:00
fgraph.c tracing: Fix ftrace_graph_get_ret_stack() to use task and not current 2018-12-22 08:21:03 -05:00
ftrace_internal.h ftrace: Create new ftrace_internal.h header 2018-12-08 20:54:06 -05:00
ftrace.c module: Fix livepatch/ftrace module text permissions race 2019-06-14 17:01:50 -04:00
Kconfig tracing: stop making gpio tracing configurable 2019-04-08 15:11:48 +02:00
Makefile tracing: Add unified dynamic event framework 2018-12-08 20:54:09 -05:00
power-traces.c
preemptirq_delay_test.c tracing: Use trace_clock_local() for looping in preemptirq_delay_test.c 2018-10-17 15:35:33 -04:00
ring_buffer_benchmark.c ring-buffer: Fix mispelling of Calculate 2019-05-08 12:15:12 -04:00
ring_buffer.c The major changes in this tracing update includes: 2019-05-15 16:05:47 -07:00
rpm-traces.c
trace_benchmark.c rcu: Rename cond_resched_rcu_qs() to cond_resched_tasks_rcu_qs() 2018-05-15 10:27:29 -07:00
trace_benchmark.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_branch.c x86/uaccess, ftrace: Fix ftrace_likely_update() vs. SMAP 2019-04-03 11:02:24 +02:00
trace_clock.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
trace_dynevent.c tracing: initialize variable in create_dyn_event() 2019-03-26 08:35:36 -04:00
trace_dynevent.h tracing: Add unified dynamic event framework 2018-12-08 20:54:09 -05:00
trace_entries.h tracing: Change the function format to display function names by perf 2019-02-11 14:53:43 -05:00
trace_event_perf.c tracing/perf: Use strndup_user() instead of buggy open-coded version 2019-02-21 10:35:10 -05:00
trace_events_filter_test.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_events_filter.c tracing: Avoid memory leak in predicate_parse() 2019-05-28 16:27:58 -04:00
trace_events_hist.c tracing: Add a check_val() check before updating cond_snapshot() track_val 2019-05-21 12:48:07 -04:00
trace_events_trigger.c tracing: Add trace_array parameter to create_event_filter() 2019-04-08 09:22:28 -04:00
trace_events.c tracing: Fix partial reading of trace event's id file 2019-05-08 12:15:12 -04:00
trace_export.c tracing: Add trigger file for trace_markers tracefs/ftrace/print 2018-05-29 08:28:53 -04:00
trace_functions_graph.c tracing: Put a margin between flags and duration for wakeup tracers 2019-02-06 11:56:19 -05:00
trace_functions.c
trace_hwlat.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
trace_irqsoff.c The biggest change for this release is in the histogram code. 2019-03-11 17:01:32 -07:00
trace_kdb.c tracing: Silence GCC 9 array bounds warning 2019-05-25 23:04:30 -04:00
trace_kprobe_selftest.c selftest/ftrace: Move kprobe selftest function to separate compile unit 2018-07-30 18:41:04 -04:00
trace_kprobe_selftest.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_kprobe.c tracing: Use tracing error_log with probe events 2019-04-02 18:24:07 -04:00
trace_mmiotrace.c
trace_nop.c
trace_output.c tracing: Fix out-of-range read in trace_stack_print() 2019-06-14 16:28:42 -04:00
trace_output.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_preemptirq.c kprobes: Prohibit probing on hardirq tracers 2019-02-13 08:16:40 +01:00
trace_printk.c tracing: Trivia spelling fix containerof() -> container_of() 2018-09-26 12:21:00 +03:00
trace_probe_tmpl.h tracing: probeevent: Do not accumulate on ret variable 2019-05-08 12:15:11 -04:00
trace_probe.c tracing: Replace kzalloc with kcalloc 2019-05-08 12:15:12 -04:00
trace_probe.h tracing: uprobes: Re-enable $comm support for uprobe events 2019-05-08 12:15:11 -04:00
trace_sched_switch.c
trace_sched_wakeup.c tracing: Add conditional snapshot 2019-02-20 13:51:06 -05:00
trace_selftest_dynamic.c
trace_selftest.c function_graph: Have selftest also emulate tr->reset() as it did with tr->init() 2019-04-21 19:46:56 -04:00
trace_seq.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
trace_stack.c tracing: Remove the last struct stack_trace usage 2019-04-29 12:37:56 +02:00
trace_stat.c
trace_stat.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00
trace_syscalls.c syscalls: Remove start and number from syscall_get_arguments() args 2019-04-05 09:26:43 -04:00
trace_uprobe.c tracing/uprobe: Fix obsolete comment on trace_uprobe_create() 2019-06-14 17:00:36 -04:00
trace.c tracing: Make two symbols static 2019-06-14 16:49:26 -04:00
trace.h tracing: Silence GCC 9 array bounds warning 2019-05-25 23:04:30 -04:00
tracing_map.c tracing: Add SPDX License format tags to tracing files 2018-08-16 19:08:06 -04:00
tracing_map.h tracing: Fix SPDX format headers to use C++ style comments 2018-08-16 19:08:06 -04:00