linux.git/kernel/trace/fprobe.c, branch v6.1.168

fprobe: Fix to ensure the number of active retprobes is not zero

2023-10-25T10:03:12+00:00

[ Upstream commit 700b2b439766e8aab8a7174991198497345bd411 ]

The number of active retprobes can be zero but it is not acceptable,
so return EINVAL error if detected.

Link: https://lore.kernel.org/all/169750018550.186853.11198884812017796410.stgit@devnote2/

Reported-by: wuqiang.matt 
Closes: https://lore.kernel.org/all/20231016222103.cb9f426edc60220eabd8aa6a@kernel.org/
Fixes: 5b0ab78998e3 ("fprobe: Add exit_handler support")
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Sasha Levin

fprobe: Add nr_maxactive to specify rethook_node pool size

2023-10-25T10:03:12+00:00

[ Upstream commit 59a7a298565aa0ce44ce8e4fbcbb89a19730013a ]

Add nr_maxactive to specify rethook_node pool size. This means
the maximum number of actively running target functions concurrently
for probing by exit_handler. Note that if the running function is
preempted or sleep, it is still counted as 'active'.

Link: https://lkml.kernel.org/r/167526697917.433354.17779774988245113106.stgit@mhiramat.roam.corp.google.com

Cc: Florent Revest 
Cc: Mark Rutland 
Cc: Will Deacon 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Steven Rostedt (Google) 
Stable-dep-of: 700b2b439766 ("fprobe: Fix to ensure the number of active retprobes is not zero")
Signed-off-by: Sasha Levin

fprobe: Pass entry_data to handlers

2023-10-25T10:03:12+00:00

[ Upstream commit 76d0de5729c0569c4071e7f21fcab394e502f03a ]

Pass the private entry_data to the entry and exit handlers so that
they can share the context data, something like saved function
arguments etc.
User must specify the private entry_data size by @entry_data_size
field before registering the fprobe.

Link: https://lkml.kernel.org/r/167526696173.433354.17408372048319432574.stgit@mhiramat.roam.corp.google.com

Cc: Florent Revest 
Cc: Mark Rutland 
Cc: Will Deacon 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Steven Rostedt (Google) 
Stable-dep-of: 700b2b439766 ("fprobe: Fix to ensure the number of active retprobes is not zero")
Signed-off-by: Sasha Levin

fprobe: Ensure running fprobe_exit_handler() finished before calling rethook_free()

2023-07-23T11:49:46+00:00

commit 195b9cb5b288fec1c871ef89f78cc9a7461aad3a upstream.

Ensure running fprobe_exit_handler() has finished before
calling rethook_free() in the unregister_fprobe() so that caller can free
the fprobe right after unregister_fprobe().

unregister_fprobe() ensured that all running fprobe_entry/exit_handler()
have finished by calling unregister_ftrace_function() which synchronizes
RCU. But commit 5f81018753df ("fprobe: Release rethook after the ftrace_ops
is unregistered") changed to call rethook_free() after
unregister_ftrace_function(). So call rethook_stop() to make rethook
disabled before unregister_ftrace_function() and ensure it again.

Here is the possible code flow that can call the exit handler after
unregister_fprobe().

------
 CPU1                              CPU2
 call unregister_fprobe(fp)
 ...
                                   __fprobe_handler()
                                   rethook_hook() on probed function
 unregister_ftrace_function()
                                   return from probed function
                                   rethook hooks
                                   find rh->handler == fprobe_exit_handler
                                   call fprobe_exit_handler()
 rethook_free():
   set rh->handler = NULL;
 return from unreigster_fprobe;
                                   call fp->exit_handler() <- (*)
------

(*) At this point, the exit handler is called after returning from
unregister_fprobe().

This fixes it as following;
------
 CPU1                              CPU2
 call unregister_fprobe()
 ...
 rethook_stop():
   set rh->handler = NULL;
                                   __fprobe_handler()
                                   rethook_hook() on probed function
 unregister_ftrace_function()
                                   return from probed function
                                   rethook hooks
                                   find rh->handler == NULL
                                   return from rethook
 rethook_free()
 return from unreigster_fprobe;
------

Link: https://lore.kernel.org/all/168873859949.156157.13039240432299335849.stgit@devnote2/

Fixes: 5f81018753df ("fprobe: Release rethook after the ftrace_ops is unregistered")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) 
Reviewed-by: Steven Rostedt (Google) 
Signed-off-by: Greg Kroah-Hartman

fprobe: Release rethook after the ftrace_ops is unregistered

2023-07-23T11:49:46+00:00

commit 5f81018753dfd4989e33ece1f0cb6b8aae498b82 upstream.

While running bpf selftests it's possible to get following fault:

  general protection fault, probably for non-canonical address \
  0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC NOPTI
  ...
  Call Trace:
   
   fprobe_handler+0xc1/0x270
   ? __pfx_bpf_testmod_init+0x10/0x10
   ? __pfx_bpf_testmod_init+0x10/0x10
   ? bpf_fentry_test1+0x5/0x10
   ? bpf_fentry_test1+0x5/0x10
   ? bpf_testmod_init+0x22/0x80
   ? do_one_initcall+0x63/0x2e0
   ? rcu_is_watching+0xd/0x40
   ? kmalloc_trace+0xaf/0xc0
   ? do_init_module+0x60/0x250
   ? __do_sys_finit_module+0xac/0x120
   ? do_syscall_64+0x37/0x90
   ? entry_SYSCALL_64_after_hwframe+0x72/0xdc
   

In unregister_fprobe function we can't release fp->rethook while it's
possible there are some of its users still running on another cpu.

Moving rethook_free call after fp->ops is unregistered with
unregister_ftrace_function call.

Link: https://lore.kernel.org/all/20230615115236.3476617-1-jolsa@kernel.org/

Fixes: 5b0ab78998e3 ("fprobe: Add exit_handler support")
Cc: stable@vger.kernel.org
Reviewed-by: Steven Rostedt (Google) 
Signed-off-by: Jiri Olsa 
Acked-by: Masami Hiramatsu (Google) 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

tracing/fprobe: Fix to check whether fprobe is registered correctly

2022-11-03T23:50:07+00:00

Since commit ab51e15d535e ("fprobe: Introduce FPROBE_FL_KPROBE_SHARED flag
for fprobe") introduced fprobe_kprobe_handler() for fprobe::ops::func,
unregister_fprobe() fails to unregister the registered if user specifies
FPROBE_FL_KPROBE_SHARED flag.
Moreover, __register_ftrace_function() is possible to change the
ftrace_ops::func, thus we have to check fprobe::ops::saved_func instead.

To check it correctly, it should confirm the fprobe::ops::saved_func is
either fprobe_handler() or fprobe_kprobe_handler().

Link: https://lore.kernel.org/all/166677683946.1459107.15997653945538644683.stgit@devnote3/

Fixes: cad9931f64dc ("fprobe: Add ftrace based probe APIs")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google)

fprobe: Check rethook_alloc() return in rethook initialization

2022-11-03T23:50:00+00:00

Check if fp->rethook succeeded to be allocated. Otherwise, if
rethook_alloc() fails, then we end up dereferencing a NULL pointer in
rethook_add_node().

Link: https://lore.kernel.org/all/20221025031209.954836-1-rafaelmendsr@gmail.com/

Fixes: 5b0ab78998e3 ("fprobe: Add exit_handler support")
Cc: stable@vger.kernel.org
Signed-off-by: Rafael Mendonca 
Acked-by: Steven Rostedt (Google) 
Acked-by: Masami Hiramatsu (Google) 
Signed-off-by: Masami Hiramatsu (Google)

fprobe: Resolve symbols with ftrace_lookup_symbols

2022-05-10T21:42:06+00:00

Using ftrace_lookup_symbols to speed up symbols lookup
in register_fprobe_syms API.

Acked-by: Masami Hiramatsu 
Signed-off-by: Jiri Olsa 
Link: https://lore.kernel.org/r/20220510122616.2652285-4-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov

fprobe: Fix sparse warning for acccessing __rcu ftrace_hash

2022-03-29T02:05:40+00:00

Since ftrace_ops::local_hash::filter_hash field is an __rcu pointer,
we have to use rcu_access_pointer() to access it.

Reported-by: kernel test robot 
Signed-off-by: Masami Hiramatsu 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/164802093635.1732982.4938094876018890866.stgit@devnote2

fprobe: Fix smatch type mismatch warning

2022-03-29T02:05:40+00:00

Fix the type mismatching warning of 'rethook_node vs fprobe_rethook_node'
found by Smatch.

Reported-by: Dan Carpenter 
Signed-off-by: Masami Hiramatsu 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/164802092611.1732982.12268174743437084619.stgit@devnote2