[for-next][PATCH 0/2] tracefs: Updates for 7.3

[for-next][PATCH 0/2] tracefs: Updates for 7.3

[Steven Rostedt]

  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
tracefs/for-next

Head SHA1: 43a17abc83c6402bffac80a6dd434f8555f457e8


Anubhav Shelat (1):
      eventfs: Define event fields before directory creation

Steven Rostedt (1):
      eventfs: Add warning for out of bounds pos in __eventfs_iterate()

----
 fs/tracefs/event_inode.c    |  4 ++++
 kernel/trace/trace_events.c | 13 +++++++------
 2 files changed, 11 insertions(+), 6 deletions(-)

[for-next][PATCH 1/2] eventfs: Define event fields before directory creation

[Steven Rostedt]

From: Anubhav Shelat <ashelat@redhat.com>

Move the event_define_fields() call in event_create_dir() before the
eventfs directory creation. Previously, a failure after directory
creation wouldn't clean up eventfs_inode because the error path didn't
call eventfs_remove_dir(). This eliminates the need to clean up the
eventfs directories if event_define_fields() fails.

Link: https://patch.msgid.link/20260715135231.338535-3-ashelat@redhat.com
Signed-off-by: Anubhav Shelat <ashelat@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_events.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index c01b10b99f67..ea608519f4b1 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -3192,6 +3192,13 @@ event_create_dir(struct eventfs_inode *parent, struct trace_event_file *file)
 	if (WARN_ON_ONCE(strcmp(call->class->system, TRACE_SYSTEM) == 0))
 		return -ENODEV;
 
+	ret = event_define_fields(call);
+	if (ret < 0) {
+		pr_warn("Could not initialize trace point events/%s\n",
+			trace_event_name(call));
+		return ret;
+	}
+
 	e_events = event_subsystem_dir(tr, call->class->system, file, parent);
 	if (!e_events)
 		return -ENOMEM;
@@ -3210,12 +3217,6 @@ event_create_dir(struct eventfs_inode *parent, struct trace_event_file *file)
 
 	file->ei = ei;
 
-	ret = event_define_fields(call);
-	if (ret < 0) {
-		pr_warn("Could not initialize trace point events/%s\n", name);
-		return ret;
-	}
-
 	/* Gets decremented on freeing of the "enable" file */
 	event_file_get(file);
 
-- 
2.53.0

[for-next][PATCH 2/2] eventfs: Add warning for out of bounds pos in __eventfs_iterate()

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

Sashiko has complained about out of bounds issues if ctx->pos isn't what
is expected in __eventfs_iterate()[1]. This would be an issue if the logic
that calls __eventfs_iterate() didn't already prevent the code from going
out of bounds.

The issue Sashiko brings up is if a user uses lseek64() to put in a
position like 0x100000000 which will overflow the integer used to iterate
the files. This should never be an issue because both tracefs and eventfs
uses the default "maxbytes" for its superblock "s_maxbytes" field which is
defined as:

  fs/super.c:     s->s_maxbytes = MAX_NON_LFS;
  include/linux/fs.h:#define      MAX_NON_LFS     ((1UL<<31) - 1)

Where MAX_NON_LFS turns into 0x7fffffff.

Testing this with code to try to pass 0x100000000 to lseek64() to a
eventfs directory returns -EINVAL.

But relying on logic for the integrity of a function is not very robust.
Add a WARN_ON_ONCE() in case the ctx->pos is out of the expected range.

[1] https://sashiko.dev/#/patchset/20260810160708.3460a2fd%40gandalf.local.home

Link: https://patch.msgid.link/20260810175928.5f4d9d5c@gandalf.local.home
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 fs/tracefs/event_inode.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 39c7a34531e8..96a561970fcc 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -584,6 +584,10 @@ static int eventfs_iterate(struct file *file, struct dir_context *ctx)
 	if (!(ti->flags & TRACEFS_EVENT_INODE))
 		return -EINVAL;
 
+	/* Logic should prevent ctx->pos from going out of range */
+	if (WARN_ON_ONCE(ctx->pos < 2 || ctx->pos > 0x7fffffffULL))
+		return -EINVAL;
+
 	c = ctx->pos - 2;
 
 	guard(srcu)(&eventfs_srcu);
-- 
2.53.0