linux-stable.git/kernel/trace/ftrace.c, branch v6.1.136

ftrace: Add cond_resched() to ftrace_graph_set_hash()

2025-04-25T08:43:44+00:00

commit 42ea22e754ba4f2b86f8760ca27f6f71da2d982c upstream.

When the kernel contains a large number of functions that can be traced,
the loop in ftrace_graph_set_hash() may take a lot of time to execute.
This may trigger the softlockup watchdog.

Add cond_resched() within the loop to allow the kernel to remain
responsive even when processing a large number of functions.

This matches the cond_resched() that is used in other locations of the
code that iterates over all functions that can be traced.

Cc: stable@vger.kernel.org
Fixes: b9b0c831bed26 ("ftrace: Convert graph filter to use hash tables")
Link: https://lore.kernel.org/tencent_3E06CE338692017B5809534B9C5C03DA7705@qq.com
Signed-off-by: zhoumin 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

ftrace: Avoid potential division by zero in function_stat_show()

2025-03-07T15:56:47+00:00

commit a1a7eb89ca0b89dc1c326eeee2596f263291aca3 upstream.

Check whether denominator expression x * (x - 1) * 1000 mod {2^32, 2^64}
produce zero and skip stddev computation in that case.

For now don't care about rec->counter * rec->counter overflow because
rec->time * rec->time overflow will likely happen earlier.

Cc: stable@vger.kernel.org
Cc: Wen Yang 
Cc: Mark Rutland 
Cc: Mathieu Desnoyers 
Link: https://lore.kernel.org/20250206090156.1561783-1-kniv@yandex-team.ru
Fixes: e31f7939c1c27 ("ftrace: Avoid potential division by zero in function profiler")
Signed-off-by: Nikolay Kuratov 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

ftrace: Do not add duplicate entries in subops manager ops

2025-03-07T15:56:40+00:00

commit 8eb4b09e0bbd30981305643229fe7640ad41b667 upstream.

Check if a function is already in the manager ops of a subops. A manager
ops contains multiple subops, and if two or more subops are tracing the
same function, the manager ops only needs a single entry in its hash.

Cc: stable@vger.kernel.org
Cc: Mark Rutland 
Cc: Mathieu Desnoyers 
Cc: Andrew Morton 
Cc: Sven Schnelle 
Cc: Vasily Gorbik 
Cc: Alexander Gordeev 
Link: https://lore.kernel.org/20250220202055.226762894@goodmis.org
Fixes: 4f554e955614f ("ftrace: Add ftrace_set_filter_ips function")
Tested-by: Heiko Carstens 
Reviewed-by: Masami Hiramatsu (Google) 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

ftrace: Fix regression with module command in stack_trace_filter

2024-12-14T18:54:13+00:00

commit 45af52e7d3b8560f21d139b3759735eead8b1653 upstream.

When executing the following command:

    # echo "write*:mod:ext3" > /sys/kernel/tracing/stack_trace_filter

The current mod command causes a null pointer dereference. While commit
0f17976568b3f ("ftrace: Fix regression with module command in stack_trace_filter")
has addressed part of the issue, it left a corner case unhandled, which still
results in a kernel crash.

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu 
Cc: Mark Rutland 
Cc: Mathieu Desnoyers 
Link: https://lore.kernel.org/20241120052750.275463-1-guoweikang.kernel@gmail.com
Fixes: 04ec7bb642b77 ("tracing: Have the trace_array hold the list of registered func probes");
Signed-off-by: guoweikang 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

ftrace: Fix possible use-after-free issue in ftrace_location()

2024-06-12T09:02:54+00:00

commit e60b613df8b6253def41215402f72986fee3fc8d upstream.

KASAN reports a bug:

  BUG: KASAN: use-after-free in ftrace_location+0x90/0x120
  Read of size 8 at addr ffff888141d40010 by task insmod/424
  CPU: 8 PID: 424 Comm: insmod Tainted: G        W          6.9.0-rc2+
  [...]
  Call Trace:
   
   dump_stack_lvl+0x68/0xa0
   print_report+0xcf/0x610
   kasan_report+0xb5/0xe0
   ftrace_location+0x90/0x120
   register_kprobe+0x14b/0xa40
   kprobe_init+0x2d/0xff0 [kprobe_example]
   do_one_initcall+0x8f/0x2d0
   do_init_module+0x13a/0x3c0
   load_module+0x3082/0x33d0
   init_module_from_file+0xd2/0x130
   __x64_sys_finit_module+0x306/0x440
   do_syscall_64+0x68/0x140
   entry_SYSCALL_64_after_hwframe+0x71/0x79

The root cause is that, in lookup_rec(), ftrace record of some address
is being searched in ftrace pages of some module, but those ftrace pages
at the same time is being freed in ftrace_release_mod() as the
corresponding module is being deleted:

           CPU1                       |      CPU2
  register_kprobes() {                | delete_module() {
    check_kprobe_address_safe() {     |
      arch_check_ftrace_location() {  |
        ftrace_location() {           |
          lookup_rec() // USE!        |   ftrace_release_mod() // Free!

To fix this issue:
  1. Hold rcu lock as accessing ftrace pages in ftrace_location_range();
  2. Use ftrace_location_range() instead of lookup_rec() in
     ftrace_location();
  3. Call synchronize_rcu() before freeing any ftrace pages both in
     ftrace_process_locs()/ftrace_release_mod()/ftrace_free_mem().

Link: https://lore.kernel.org/linux-trace-kernel/20240509192859.1273558-1-zhengyejian1@huawei.com

Cc: stable@vger.kernel.org
Cc: 
Cc: 
Cc: 
Fixes: ae6aa16fdc16 ("kprobes: introduce ftrace based optimization")
Suggested-by: Steven Rostedt 
Signed-off-by: Zheng Yejian 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

ftrace: Fix possible warning on checking all pages used in ftrace_process_locs()

2023-07-23T11:49:44+00:00

commit 26efd79c4624294e553aeaa3439c646729bad084 upstream.

As comments in ftrace_process_locs(), there may be NULL pointers in
mcount_loc section:
 > Some architecture linkers will pad between
 > the different mcount_loc sections of different
 > object files to satisfy alignments.
 > Skip any NULL pointers.

After commit 20e5227e9f55 ("ftrace: allow NULL pointers in mcount_loc"),
NULL pointers will be accounted when allocating ftrace pages but skipped
before adding into ftrace pages, this may result in some pages not being
used. Then after commit 706c81f87f84 ("ftrace: Remove extra helper
functions"), warning may occur at:
  WARN_ON(pg->next);

To fix it, only warn for case that no pointers skipped but pages not used
up, then free those unused pages after releasing ftrace_lock.

Link: https://lore.kernel.org/linux-trace-kernel/20230712060452.3175675-1-zhengyejian1@huawei.com

Cc: stable@vger.kernel.org
Fixes: 706c81f87f84 ("ftrace: Remove extra helper functions")
Suggested-by: Steven Rostedt 
Signed-off-by: Zheng Yejian 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

ftrace: Fix issue that 'direct->addr' not restored in modify_ftrace_direct()

2023-04-13T14:55:32+00:00

commit 2a2d8c51defb446e8d89a83f42f8e5cd529111e9 upstream.

Syzkaller report a WARNING: "WARN_ON(!direct)" in modify_ftrace_direct().

Root cause is 'direct->addr' was changed from 'old_addr' to 'new_addr' but
not restored if error happened on calling ftrace_modify_direct_caller().
Then it can no longer find 'direct' by that 'old_addr'.

To fix it, restore 'direct->addr' to 'old_addr' explicitly in error path.

Link: https://lore.kernel.org/linux-trace-kernel/20230330025223.1046087-1-zhengyejian1@huawei.com

Cc: stable@vger.kernel.org
Cc: 
Cc: 
Cc: 
Cc: 
Fixes: 8a141dd7f706 ("ftrace: Fix modify_ftrace_direct.")
Signed-off-by: Zheng Yejian 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

ftrace: Fix invalid address access in lookup_rec() when index is 0

2023-03-22T12:34:02+00:00

commit ee92fa443358f4fc0017c1d0d325c27b37802504 upstream.

KASAN reported follow problem:

 BUG: KASAN: use-after-free in lookup_rec
 Read of size 8 at addr ffff000199270ff0 by task modprobe
 CPU: 2 Comm: modprobe
 Call trace:
  kasan_report
  __asan_load8
  lookup_rec
  ftrace_location
  arch_check_ftrace_location
  check_kprobe_address_safe
  register_kprobe

When checking pg->records[pg->index - 1].ip in lookup_rec(), it can get a
pg which is newly added to ftrace_pages_start in ftrace_process_locs().
Before the first pg->index++, index is 0 and accessing pg->records[-1].ip
will cause this problem.

Don't check the ip when pg->index is 0.

Link: https://lore.kernel.org/linux-trace-kernel/20230309080230.36064-1-chenzhongjin@huawei.com

Cc: stable@vger.kernel.org
Fixes: 9644302e3315 ("ftrace: Speed up search by skipping pages by address")
Suggested-by: Steven Rostedt (Google) 
Signed-off-by: Chen Zhongjin 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

ftrace: Export ftrace_free_filter() to modules

2023-02-01T07:34:37+00:00

commit 8be9fbd5345da52f4a74f7f81d55ff9fa0a2958e upstream.

Setting filters on an ftrace ops results in some memory being allocated
for the filter hashes, which must be freed before the ops can be freed.
This can be done by removing every individual element of the hash by
calling ftrace_set_filter_ip() or ftrace_set_filter_ips() with `remove`
set, but this is somewhat error prone as it's easy to forget to remove
an element.

Make it easier to clean this up by exporting ftrace_free_filter(), which
can be used to clean up all of the filter hashes after an ftrace_ops has
been unregistered.

Using this, fix the ftrace-direct* samples to free hashes prior to being
unloaded. All other code either removes individual filters explicitly or
is built-in and already calls ftrace_free_filter().

Link: https://lkml.kernel.org/r/20230103124912.2948963-3-mark.rutland@arm.com

Cc: stable@vger.kernel.org
Cc: Florent Revest 
Cc: Masami Hiramatsu 
Fixes: e1067a07cfbc ("ftrace/samples: Add module to test multi direct modify interface")
Fixes: 5fae941b9a6f ("ftrace/samples: Add multi direct interface test module")
Reviewed-by: Masami Hiramatsu (Google) 
Reviewed-by: Steven Rostedt (Google) 
Signed-off-by: Mark Rutland 
Signed-off-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

ftrace: Fix null pointer dereference in ftrace_add_mod()

2022-11-17T22:16:44+00:00

The @ftrace_mod is allocated by kzalloc(), so both the members {prev,next}
of @ftrace_mode->list are NULL, it's not a valid state to call list_del().
If kstrdup() for @ftrace_mod->{func|module} fails, it goes to @out_free
tag and calls free_ftrace_mod() to destroy @ftrace_mod, then list_del()
will write prev->next and next->prev, where null pointer dereference
happens.

BUG: kernel NULL pointer dereference, address: 0000000000000008
Oops: 0002 [#1] PREEMPT SMP NOPTI
Call Trace:
 
 ftrace_mod_callback+0x20d/0x220
 ? do_filp_open+0xd9/0x140
 ftrace_process_regex.isra.51+0xbf/0x130
 ftrace_regex_write.isra.52.part.53+0x6e/0x90
 vfs_write+0xee/0x3a0
 ? __audit_filter_op+0xb1/0x100
 ? auditd_test_task+0x38/0x50
 ksys_write+0xa5/0xe0
 do_syscall_64+0x3a/0x90
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
Kernel panic - not syncing: Fatal exception

So call INIT_LIST_HEAD() to initialize the list member to fix this issue.

Link: https://lkml.kernel.org/r/20221116015207.30858-1-xiujianfeng@huawei.com

Cc: stable@vger.kernel.org
Fixes: 673feb9d76ab ("ftrace: Add :mod: caching infrastructure to trace_array")
Signed-off-by: Xiu Jianfeng 
Signed-off-by: Steven Rostedt (Google)