tracing: Fix uaf issue when open the hist or hist_debug file

Zheng Yejian · rostedt · commit 1cc111b9cddc · 2023-12-13T23:29:59.000-05:00
KASAN report following issue. The root cause is when opening 'hist' file of an instance and accessing 'trace_event_file' in hist_show(), but 'trace_event_file' has been freed due to the instance being removed. 'hist_debug' file has the same problem. To fix it, call tracing_{open,release}_file_tr() in file_operations callback to have the ref count and avoid 'trace_event_file' being freed. BUG: KASAN: slab-use-after-free in hist_show+0x11e0/0x1278 Read of size 8 at addr ffff242541e336b8 by task head/190 CPU: 4 PID: 190 Comm: head Not tainted 6.7.0-rc5-g26aff849438c torvalds#133 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x98/0xf8 show_stack+0x1c/0x30 dump_stack_lvl+0x44/0x58 print_report+0xf0/0x5a0 kasan_report+0x80/0xc0 __asan_report_load8_noabort+0x1c/0x28 hist_show+0x11e0/0x1278 seq_read_iter+0x344/0xd78 seq_read+0x128/0x1c0 vfs_read+0x198/0x6c8 ksys_read+0xf4/0x1e0 __arm64_sys_read+0x70/0xa8 invoke_syscall+0x70/0x260 el0_svc_common.constprop.0+0xb0/0x280 do_el0_svc+0x44/0x60 el0_svc+0x34/0x68 el0t_64_sync_handler+0xb8/0xc0 el0t_64_sync+0x168/0x170 Allocated by task 188: kasan_save_stack+0x28/0x50 kasan_set_track+0x28/0x38 kasan_save_alloc_info+0x20/0x30 __kasan_slab_alloc+0x6c/0x80 kmem_cache_alloc+0x15c/0x4a8 trace_create_new_event+0x84/0x348 __trace_add_new_event+0x18/0x88 event_trace_add_tracer+0xc4/0x1a0 trace_array_create_dir+0x6c/0x100 trace_array_create+0x2e8/0x568 instance_mkdir+0x48/0x80 tracefs_syscall_mkdir+0x90/0xe8 vfs_mkdir+0x3c4/0x610 do_mkdirat+0x144/0x200 __arm64_sys_mkdirat+0x8c/0xc0 invoke_syscall+0x70/0x260 el0_svc_common.constprop.0+0xb0/0x280 do_el0_svc+0x44/0x60 el0_svc+0x34/0x68 el0t_64_sync_handler+0xb8/0xc0 el0t_64_sync+0x168/0x170 Freed by task 191: kasan_save_stack+0x28/0x50 kasan_set_track+0x28/0x38 kasan_save_free_info+0x34/0x58 __kasan_slab_free+0xe4/0x158 kmem_cache_free+0x19c/0x508 event_file_put+0xa0/0x120 remove_event_file_dir+0x180/0x320 event_trace_del_tracer+0xb0/0x180 __remove_instance+0x224/0x508 instance_rmdir+0x44/0x78 tracefs_syscall_rmdir+0xbc/0x140 vfs_rmdir+0x1cc/0x4c8 do_rmdir+0x220/0x2b8 __arm64_sys_unlinkat+0xc0/0x100 invoke_syscall+0x70/0x260 el0_svc_common.constprop.0+0xb0/0x280 do_el0_svc+0x44/0x60 el0_svc+0x34/0x68 el0t_64_sync_handler+0xb8/0xc0 el0t_64_sync+0x168/0x170 Link: https://lore.kernel.org/linux-trace-kernel/20231214012153.676155-1-zhengyejian1@huawei.com Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
@@ -4968,6 +4968,12 @@ int tracing_release_file_tr(struct inode *inode, struct file *filp)
 	return 0;
 }
 
+int tracing_single_release_file_tr(struct inode *inode, struct file *filp)
+{
+	tracing_release_file_tr(inode, filp);
+	return single_release(inode, filp);
+}
+
 static int tracing_mark_open(struct inode *inode, struct file *filp)
 {
 	stream_open(inode, filp);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
@@ -617,6 +617,7 @@ int tracing_open_generic(struct inode *inode, struct file *filp);
 int tracing_open_generic_tr(struct inode *inode, struct file *filp);
 int tracing_open_file_tr(struct inode *inode, struct file *filp);
 int tracing_release_file_tr(struct inode *inode, struct file *filp);
+int tracing_single_release_file_tr(struct inode *inode, struct file *filp);
 bool tracing_is_disabled(void);
 bool tracer_tracing_is_on(struct trace_array *tr);
 void tracer_tracing_on(struct trace_array *tr);
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
@@ -5623,18 +5623,20 @@ static int event_hist_open(struct inode *inode, struct file *file)
 {
 	int ret;
 
-	ret = security_locked_down(LOCKDOWN_TRACEFS);
+	ret = tracing_open_file_tr(inode, file);
 	if (ret)
 		return ret;
 
+	/* Clear private_data to avoid warning in single_open() */
+	file->private_data = NULL;
 	return single_open(file, hist_show, file);
 }
 
 const struct file_operations event_hist_fops = {
 	.open = event_hist_open,
 	.read = seq_read,
 	.llseek = seq_lseek,
-	.release = single_release,
+	.release = tracing_single_release_file_tr,
 };
 
 #ifdef CONFIG_HIST_TRIGGERS_DEBUG
@@ -5900,18 +5902,20 @@ static int event_hist_debug_open(struct inode *inode, struct file *file)
 {
 	int ret;
 
-	ret = security_locked_down(LOCKDOWN_TRACEFS);
+	ret = tracing_open_file_tr(inode, file);
 	if (ret)
 		return ret;
 
+	/* Clear private_data to avoid warning in single_open() */
+	file->private_data = NULL;
 	return single_open(file, hist_debug_show, file);
 }
 
 const struct file_operations event_hist_debug_fops = {
 	.open = event_hist_debug_open,
 	.read = seq_read,
 	.llseek = seq_lseek,
-	.release = single_release,
+	.release = tracing_single_release_file_tr,
 };
 #endif
 

Original file line number	Diff line number	Diff line change
`@@ -4968,6 +4968,12 @@ int tracing_release_file_tr(struct inode inode, struct file filp)`
`4968`	`4968`	`return 0;`
`4969`	`4969`	`}`
`4970`	`4970`
	`4971`	`+int tracing_single_release_file_tr(struct inode inode, struct file filp)`
	`4972`	`+{`
	`4973`	`+ tracing_release_file_tr(inode, filp);`
	`4974`	`+ return single_release(inode, filp);`
	`4975`	`+}`
	`4976`	`+`
`4971`	`4977`	`static int tracing_mark_open(struct inode inode, struct file filp)`
`4972`	`4978`	`{`
`4973`	`4979`	`stream_open(inode, filp);`