linux.git/kernel/kprobes.c, branch v6.6.72

kprobes: Fix to check symbol prefixes correctly

2024-08-14T11:58:51+00:00

[ Upstream commit 8c8acb8f26cbde665b233dd1b9bbcbb9b86822dc ]

Since str_has_prefix() takes the prefix as the 2nd argument and the string
as the first, is_cfi_preamble_symbol() always fails to check the prefix.
Fix the function parameter order so that it correctly check the prefix.

Link: https://lore.kernel.org/all/172260679559.362040.7360872132937227206.stgit@devnote2/

Fixes: de02f2ac5d8c ("kprobes: Prohibit probing on CFI preamble symbol")
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Sasha Levin

kprobe/ftrace: fix build error due to bad function definition

2024-06-27T11:49:15+00:00

commit 4b377b4868ef17b040065bd468668c707d2477a5 upstream.

Commit 1a7d0890dd4a ("kprobe/ftrace: bail out if ftrace was killed")
introduced a bad K&R function definition, which we haven't accepted in a
long long time.

Gcc seems to let it slide, but clang notices with the appropriate error:

  kernel/kprobes.c:1140:24: error: a function declaration without a prototype is deprecated in all >
   1140 | void kprobe_ftrace_kill()
        |                        ^
        |                         void

but this commit was apparently never in linux-next before it was sent
upstream, so it didn't get the appropriate build test coverage.

Fixes: 1a7d0890dd4a kprobe/ftrace: bail out if ftrace was killed
Cc: Stephen Brennan 
Cc: Masami Hiramatsu (Google) 
Cc: Guo Ren 
Cc: Steven Rostedt (Google) 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

kprobe/ftrace: bail out if ftrace was killed

2024-06-27T11:49:03+00:00

[ Upstream commit 1a7d0890dd4a502a202aaec792a6c04e6e049547 ]

If an error happens in ftrace, ftrace_kill() will prevent disarming
kprobes. Eventually, the ftrace_ops associated with the kprobes will be
freed, yet the kprobes will still be active, and when triggered, they
will use the freed memory, likely resulting in a page fault and panic.

This behavior can be reproduced quite easily, by creating a kprobe and
then triggering a ftrace_kill(). For simplicity, we can simulate an
ftrace error with a kernel module like [1]:

[1]: https://github.com/brenns10/kernel_stuff/tree/master/ftrace_killer

  sudo perf probe --add commit_creds
  sudo perf trace -e probe:commit_creds
  # In another terminal
  make
  sudo insmod ftrace_killer.ko  # calls ftrace_kill(), simulating bug
  # Back to perf terminal
  # ctrl-c
  sudo perf probe --del commit_creds

After a short period, a page fault and panic would occur as the kprobe
continues to execute and uses the freed ftrace_ops. While ftrace_kill()
is supposed to be used only in extreme circumstances, it is invoked in
FTRACE_WARN_ON() and so there are many places where an unexpected bug
could be triggered, yet the system may continue operating, possibly
without the administrator noticing. If ftrace_kill() does not panic the
system, then we should do everything we can to continue operating,
rather than leave a ticking time bomb.

Link: https://lore.kernel.org/all/20240501162956.229427-1-stephen.s.brennan@oracle.com/

Signed-off-by: Stephen Brennan 
Acked-by: Masami Hiramatsu (Google) 
Acked-by: Guo Ren 
Reviewed-by: Steven Rostedt (Google) 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Sasha Levin

kprobes: Fix possible use-after-free issue on kprobe registration

2024-04-17T09:19:34+00:00

commit 325f3fb551f8cd672dbbfc4cf58b14f9ee3fc9e8 upstream.

When unloading a module, its state is changing MODULE_STATE_LIVE ->
 MODULE_STATE_GOING -> MODULE_STATE_UNFORMED. Each change will take
a time. `is_module_text_address()` and `__module_text_address()`
works with MODULE_STATE_LIVE and MODULE_STATE_GOING.
If we use `is_module_text_address()` and `__module_text_address()`
separately, there is a chance that the first one is succeeded but the
next one is failed because module->state becomes MODULE_STATE_UNFORMED
between those operations.

In `check_kprobe_address_safe()`, if the second `__module_text_address()`
is failed, that is ignored because it expected a kernel_text address.
But it may have failed simply because module->state has been changed
to MODULE_STATE_UNFORMED. In this case, arm_kprobe() will try to modify
non-exist module text address (use-after-free).

To fix this problem, we should not use separated `is_module_text_address()`
and `__module_text_address()`, but use only `__module_text_address()`
once and do `try_module_get(module)` which is only available with
MODULE_STATE_LIVE.

Link: https://lore.kernel.org/all/20240410015802.265220-1-zhengyejian1@huawei.com/

Fixes: 28f6c37a2910 ("kprobes: Forbid probing on trampoline and BPF code areas")
Cc: stable@vger.kernel.org
Signed-off-by: Zheng Yejian 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

kprobes: consistent rcu api usage for kretprobe holder

2023-12-13T17:45:31+00:00

commit d839a656d0f3caca9f96e9bf912fd394ac6a11bc upstream.

It seems that the pointer-to-kretprobe "rp" within the kretprobe_holder is
RCU-managed, based on the (non-rethook) implementation of get_kretprobe().
The thought behind this patch is to make use of the RCU API where possible
when accessing this pointer so that the needed barriers are always in place
and to self-document the code.

The __rcu annotation to "rp" allows for sparse RCU checking. Plain writes
done to the "rp" pointer are changed to make use of the RCU macro for
assignment. For the single read, the implementation of get_kretprobe()
is simplified by making use of an RCU macro which accomplishes the same,
but note that the log warning text will be more generic.

I did find that there is a difference in assembly generated between the
usage of the RCU macros vs without. For example, on arm64, when using
rcu_assign_pointer(), the corresponding store instruction is a
store-release (STLR) which has an implicit barrier. When normal assignment
is done, a regular store (STR) is found. In the macro case, this seems to
be a result of rcu_assign_pointer() using smp_store_release() when the
value to write is not NULL.

Link: https://lore.kernel.org/all/20231122132058.3359-1-inwardvessel@gmail.com/

Fixes: d741bf41d7c7 ("kprobes: Remove kretprobe hash")
Cc: stable@vger.kernel.org
Signed-off-by: JP Kobryn 
Acked-by: Masami Hiramatsu (Google) 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

kernel: kprobes: Use struct_size()

2023-08-23T00:38:17+00:00

Use struct_size() instead of hand-writing it, when allocating a structure
with a flex array.

This is less verbose.

Link: https://lore.kernel.org/all/20230725195424.3469242-1-ruanjinjie@huawei.com/

Signed-off-by: Ruan Jinjie 
Acked-by: Masami Hiramatsu (Google) 
Signed-off-by: Masami Hiramatsu (Google)

kprobes: Prohibit probing on CFI preamble symbol

2023-07-29T14:32:26+00:00

Do not allow to probe on "__cfi_" or "__pfx_" started symbol, because those
are used for CFI and not executed. Probing it will break the CFI.

Link: https://lore.kernel.org/all/168904024679.116016.18089228029322008512.stgit@devnote2/

Signed-off-by: Masami Hiramatsu (Google) 
Reviewed-by: Steven Rostedt (Google)

Merge tag 'probes-fixes-v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2023-07-12T19:01:16+00:00

Pull probes fixes from Masami Hiramatsu:

 - Fix fprobe's rethook release issues:

     - Release rethook after ftrace_ops is unregistered so that the
       rethook is not accessed after free.

     - Stop rethook before ftrace_ops is unregistered so that the
       rethook is NOT used after exiting unregister_fprobe()

 - Fix eprobe cleanup logic. If it attaches to multiple events and
   failes to enable one of them, rollback all enabled events correctly.

 - Fix fprobe to unlock ftrace recursion lock correctly when it missed
   by another running kprobe.

 - Cleanup kprobe to remove unnecessary NULL.

 - Cleanup kprobe to remove unnecessary 0 initializations.

* tag 'probes-fixes-v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  fprobe: Ensure running fprobe_exit_handler() finished before calling rethook_free()
  kernel: kprobes: Remove unnecessary ‘0’ values
  kprobes: Remove unnecessary ‘NULL’ values from correct_ret_addr
  fprobe: add unlock to match a succeeded ftrace_test_recursion_trylock
  kernel/trace: Fix cleanup logic of enable_trace_eprobe
  fprobe: Release rethook after the ftrace_ops is unregistered

kernel: kprobes: Remove unnecessary ‘0’ values

2023-07-10T15:50:51+00:00

it is assigned first, so it does not need to initialize the assignment.

Link: https://lore.kernel.org/all/20230711185353.3218-1-zeming@nfschina.com/

Signed-off-by: Li zeming 
Acked-by: Masami Hiramatsu (Google) 
Signed-off-by: Masami Hiramatsu (Google)

kprobes: Remove unnecessary ‘NULL’ values from correct_ret_addr

2023-07-10T15:50:35+00:00

The 'correct_ret_addr' pointer is always set in the later code, no need
to initialize it at definition time.

Link: https://lore.kernel.org/all/20230704194359.3124-1-zeming@nfschina.com/

Signed-off-by: Li zeming 
Acked-by: Masami Hiramatsu (Google) 
Signed-off-by: Masami Hiramatsu (Google)