linux-stable.git/kernel/trace, branch v7.0.8

tracing/fprobe: Check the same type fprobe on table as the unregistered one

2026-05-14T13:31:11+00:00

commit 0ac0058a74ac5765c7ce09ea630f4fdeaf4d80fa upstream.

Commit 2c67dc457bc6 ("tracing: fprobe: optimization for entry only case")
introduced a different ftrace_ops for entry-only fprobes.

However, when unregistering an fprobe, the kernel only checks if another
fprobe exists at the same address, without checking which type of fprobe
it is.
If different fprobes are registered at the same address, the same address
will be registered in both fgraph_ops and ftrace_ops, but only one of
them will be deleted when unregistering. (the one removed first will not
be deleted from the ops).

This results in junk entries remaining in either fgraph_ops or ftrace_ops.
For example:
 =======
 cd /sys/kernel/tracing

 # 'Add entry and exit events on the same place'
 echo 'f:event1 vfs_read' >> dynamic_events
 echo 'f:event2 vfs_read%return' >> dynamic_events

 # 'Enable both of them'
 echo 1 > events/fprobes/enable
 cat enabled_functions
vfs_read (2)            ->arch_ftrace_ops_list_func+0x0/0x210

 # 'Disable and remove exit event'
 echo 0 > events/fprobes/event2/enable
 echo -:event2 >> dynamic_events

 # 'Disable and remove all events'
 echo 0 > events/fprobes/enable
 echo > dynamic_events

 # 'Add another event'
 echo 'f:event3 vfs_open%return' > dynamic_events
 cat dynamic_events
f:fprobes/event3 vfs_open%return

 echo 1 > events/fprobes/enable
 cat enabled_functions
vfs_open (1)            tramp: 0xffffffffa0001000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60    subops: {ent:fprobe_fgraph_entry+0x0/0x620 ret:fprobe_return+0x0/0x150}
vfs_read (1)            tramp: 0xffffffffa0001000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60    subops: {ent:fprobe_fgraph_entry+0x0/0x620 ret:fprobe_return+0x0/0x150}
 =======

As you can see, an entry for the vfs_read remains.

To fix this issue, when unregistering, the kernel should also check if
there is the same type of fprobes still exist at the same address, and
if not, delete its entry from either fgraph_ops or ftrace_ops.

Link: https://lore.kernel.org/all/177669367993.132053.10553046138528674802.stgit@mhiramat.tok.corp.google.com/

Fixes: 2c67dc457bc6 ("tracing: fprobe: optimization for entry only case")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

tracing/probes: Limit size of event probe to 3K

2026-05-14T13:31:11+00:00

commit b2aa3b4d64e460ac606f386c24e7d8a873ce6f1a upstream.

There currently isn't a max limit an event probe can be. One could make an
event greater than PAGE_SIZE, which makes the event useless because if
it's bigger than the max event that can be recorded into the ring buffer,
then it will never be recorded.

A event probe should never need to be greater than 3K, so make that the
max size. As long as the max is less than the max that can be recorded
onto the ring buffer, it should be fine.

Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers 
Acked-by: Masami Hiramatsu (Google) 
Fixes: 93ccae7a22274 ("tracing/kprobes: Support basic types on dynamic events")
Link: https://patch.msgid.link/20260428122302.706610ba@gandalf.local.home
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

tracing/fprobe: Unregister fprobe even if memory allocation fails

2026-05-14T13:31:11+00:00

commit 1aec9e5c3e31ce1e28f914427fb7f90b91d310df upstream.

unregister_fprobe() can fail under memory pressure because of memory
allocation failure, but this maybe called from module unloading, and
usually there is no way to retry it. Moreover. trace_fprobe does not
check the return value.

To fix this problem, unregister fprobe and fprobe_hash_node even if
working memory allocation fails.
Anyway, if the last fprobe is removed, the filter will be freed.

Link: https://lore.kernel.org/all/177669365629.132053.8433032896213721288.stgit@mhiramat.tok.corp.google.com/

Fixes: 4346ba160409 ("fprobe: Rewrite fprobe on function-graph tracer")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

tracing/fprobe: Remove fprobe from hash in failure path

2026-05-14T13:31:11+00:00

commit 845947aca6814f5723ed65e556eb5ee09493f05b upstream.

When register_fprobe_ips() fails, it tries to remove a list of
fprobe_hash_node from fprobe_ip_table, but it missed to remove
fprobe itself from fprobe_table. Moreover, when removing
the fprobe_hash_node which is added to rhltable once, it must
use kfree_rcu() after removing from rhltable.

To fix these issues, this reuses unregister_fprobe() internal
code to rollback the half-way registered fprobe.

Link: https://lore.kernel.org/all/177669366417.132053.17874946321744910456.stgit@mhiramat.tok.corp.google.com/

Fixes: 4346ba160409 ("fprobe: Rewrite fprobe on function-graph tracer")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

tracing/fprobe: Avoid kcalloc() in rcu_read_lock section

2026-05-14T13:31:11+00:00

commit aa72812b49104bb5a38272fc9541feb62ca6fd32 upstream.

fprobe_remove_node_in_module() is called under RCU read locked, but
this invokes kcalloc() if there are more than 8 fprobes installed
on the module. Sashiko warns it because kcalloc() can sleep [1].

 [1] https://sashiko.dev/#/patchset/177552432201.853249.5125045538812833325.stgit%40mhiramat.tok.corp.google.com

To fix this issue, expand the batch size to 128 and do not expand
the fprobe_addr_list, but just cancel walking on fprobe_ip_table,
update fgraph/ftrace_ops and retry the loop again.

Link: https://lore.kernel.org/all/177669367206.132053.1493637946869032744.stgit@mhiramat.tok.corp.google.com/

Fixes: 0de4c70d04a4 ("tracing: fprobe: use rhltable for fprobe_ip_table")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

ring-buffer: Do not double count the reader_page

2026-05-07T04:14:08+00:00

commit 92d5a606721f759ebebf448b3bd2b7a781d50bd0 upstream.

Since the cpu_buffer->reader_page is updated if there are unwound
pages. After that update, we should skip the page if it is the
original reader_page, because the original reader_page is already
checked.

Cc: stable@vger.kernel.org
Cc: Catalin Marinas 
Cc: Will Deacon 
Cc: Mathieu Desnoyers 
Cc: Ian Rogers 
Link: https://patch.msgid.link/177701353063.2223789.1471163147644103306.stgit@mhiramat.tok.corp.google.com
Fixes: ca296d32ece3 ("tracing: ring_buffer: Rewind persistent ring buffer on reboot")
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

tracing/fprobe: Reject registration of a registered fprobe before init

2026-05-07T04:13:59+00:00

commit 6ad51ada17ed80c9a5f205b4c01c424cac8b0d46 upstream.

Reject registration of a registered fprobe which is on the fprobe
hash table before initializing fprobe.
The add_fprobe_hash() checks this re-register fprobe, but since
fprobe_init() clears hlist_array field, it is too late to check it.
It has to check the re-registration before touncing fprobe.

Link: https://lore.kernel.org/all/177669364845.132053.18375367916162315835.stgit@mhiramat.tok.corp.google.com/

Fixes: 4346ba160409 ("fprobe: Rewrite fprobe on function-graph tracer")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

tracing/probe: reject non-closed empty immediate strings

2026-04-06T00:22:42+00:00

parse_probe_arg() accepts quoted immediate strings and passes the body
after the opening quote to __parse_imm_string(). That helper currently
computes strlen(str) and immediately dereferences str[len - 1], which
underflows when the body is empty and not closed with double-quotation.

Reject empty non-closed immediate strings before checking for the closing quote.

Link: https://lore.kernel.org/all/20260401160315.88518-1-pengpeng@iscas.ac.cn/

Fixes: a42e3c4de964 ("tracing/probe: Add immediate string parameter support")
Signed-off-by: Pengpeng Hou 
Reviewed-by: Steven Rostedt (Google) 
Signed-off-by: Masami Hiramatsu (Google)

bpf: Reject sleepable kprobe_multi programs at attach time

2026-04-02T16:48:46+00:00

kprobe.multi programs run in atomic/RCU context and cannot sleep.
However, bpf_kprobe_multi_link_attach() did not validate whether the
program being attached had the sleepable flag set, allowing sleepable
helpers such as bpf_copy_from_user() to be invoked from a non-sleepable
context.

This causes a "sleeping function called from invalid context" splat:

  BUG: sleeping function called from invalid context at ./include/linux/uaccess.h:169
  in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1787, name: sudo
  preempt_count: 1, expected: 0
  RCU nest depth: 2, expected: 0

Fix this by rejecting sleepable programs early in
bpf_kprobe_multi_link_attach(), before any further processing.

Fixes: 0dcac2725406 ("bpf: Add multi kprobe link")
Signed-off-by: Varun R Mallya 
Acked-by: Kumar Kartikeya Dwivedi 
Acked-by: Leon Hwang 
Acked-by: Jiri Olsa 
Link: https://lore.kernel.org/r/20260401191126.440683-1-varunrmallya@gmail.com
Signed-off-by: Alexei Starovoitov

tracing: Drain deferred trigger frees if kthread creation fails

2026-03-28T12:32:44+00:00

Boot-time trigger registration can fail before the trigger-data cleanup
kthread exists. Deferring those frees until late init is fine, but the
post-boot fallback must still drain the deferred list if kthread
creation never succeeds.

Otherwise, boot-deferred nodes can accumulate on
trigger_data_free_list, later frees fall back to synchronously freeing
only the current object, and the older queued entries are leaked
forever.

To trigger this, add the following to the kernel command line:

  trace_event=sched_switch trace_trigger=sched_switch.traceon,sched_switch.traceon

The second traceon trigger will fail and be freed. This triggers a NULL
pointer dereference and crashes the kernel.

Keep the deferred boot-time behavior, but when kthread creation fails,
drain the whole queued list synchronously. Do the same in the late-init
drain path so queued entries are not stranded there either.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260324221326.1395799-3-atwellwea@gmail.com
Fixes: 61d445af0a7c ("tracing: Add bulk garbage collection of freeing event_trigger_data")
Signed-off-by: Wesley Atwell 
Signed-off-by: Steven Rostedt (Google)