This is a note to let you know that I've just added the patch titled
ftrace: Fix null pointer dereference in ftrace_add_mod()
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ftrace-fix-null-pointer-dereference-in-ftrace_add_mod.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 19ba6c8af9382c4c05dc6a0a79af3013b9a35cd0 Mon Sep 17 00:00:00 2001
From: Xiu Jianfeng <xiujianfeng@xxxxxxxxxx>
Date: Wed, 16 Nov 2022 09:52:07 +0800
Subject: ftrace: Fix null pointer dereference in ftrace_add_mod()
From: Xiu Jianfeng <xiujianfeng@xxxxxxxxxx>
commit 19ba6c8af9382c4c05dc6a0a79af3013b9a35cd0 upstream.
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:
<TASK>
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@xxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 673feb9d76ab ("ftrace: Add :mod: caching infrastructure to trace_array")
Signed-off-by: Xiu Jianfeng <xiujianfeng@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/trace/ftrace.c | 1 +
1 file changed, 1 insertion(+)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1331,6 +1331,7 @@ static int ftrace_add_mod(struct trace_a
if (!ftrace_mod)
return -ENOMEM;
+ INIT_LIST_HEAD(&ftrace_mod->list);
ftrace_mod->func = kstrdup(func, GFP_KERNEL);
ftrace_mod->module = kstrdup(module, GFP_KERNEL);
ftrace_mod->enable = enable;
Patches currently in stable-queue which might be from xiujianfeng@xxxxxxxxxx are
queue-4.19/ftrace-fix-null-pointer-dereference-in-ftrace_add_mod.patch
