The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x ee4e0379475e4fe723986ae96293e465014fa8d9 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2024051313-twilight-disposal-0184@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: ee4e0379475e ("eventfs: Free all of the eventfs_inode after RCU") b63db58e2fa5 ("eventfs/tracing: Add callback for release of an eventfs_inode") c3137ab6318d ("eventfs: Create eventfs_root_inode to store dentry") 264424dfdd5c ("eventfs: Restructure eventfs_inode structure to be more condensed") 5a49f996046b ("eventfs: Warn if an eventfs_inode is freed without is_freed being set") 43aa6f97c2d0 ("eventfs: Get rid of dentry pointers without refcounts") 408600be78cd ("eventfs: Remove unused d_parent pointer field") 49304c2b93e4 ("tracefs: dentry lookup crapectomy") 4fa4b010b83f ("eventfs: Initialize the tracefs inode properly") 29142dc92c37 ("tracefs: remove stale 'update_gid' code") 834bf76add3e ("eventfs: Save directory inodes in the eventfs_inode structure") 1057066009c4 ("eventfs: Use kcalloc() instead of kzalloc()") 852e46e239ee ("eventfs: Do not create dentries nor inodes in iterate_shared") 53c41052ba31 ("eventfs: Have the inodes all for files and directories all be the same") 1de94b52d5e8 ("eventfs: Shortcut eventfs_iterate() by skipping entries already read") 704f960dbee2 ("eventfs: Read ei->entries before ei->children in eventfs_iterate()") 1e4624eb5a0e ("eventfs: Do ctx->pos update for all iterations in eventfs_iterate()") e109deadb733 ("eventfs: Have eventfs_iterate() stop immediately if ei->is_freed is set") 8186fff7ab64 ("tracefs/eventfs: Use root and instance inodes as default ownership") 493ec81a8fb8 ("eventfs: Stop using dcache_readdir() for getdents()") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From ee4e0379475e4fe723986ae96293e465014fa8d9 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx> Date: Thu, 2 May 2024 16:08:22 -0400 Subject: [PATCH] eventfs: Free all of the eventfs_inode after RCU The freeing of eventfs_inode via a kfree_rcu() callback. But the content of the eventfs_inode was being freed after the last kref. This is dangerous, as changes are being made that can access the content of an eventfs_inode from an RCU loop. Instead of using kfree_rcu() use call_rcu() that calls a function to do all the freeing of the eventfs_inode after a RCU grace period has expired. Link: https://lore.kernel.org/linux-trace-kernel/20240502200905.370261163@xxxxxxxxxxx Cc: stable@xxxxxxxxxxxxxxx Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Fixes: 43aa6f97c2d03 ("eventfs: Get rid of dentry pointers without refcounts") Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index f5510e26f0f6..cc8b838bbe62 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -73,6 +73,21 @@ enum { #define EVENTFS_MODE_MASK (EVENTFS_SAVE_MODE - 1) +static void free_ei_rcu(struct rcu_head *rcu) +{ + struct eventfs_inode *ei = container_of(rcu, struct eventfs_inode, rcu); + struct eventfs_root_inode *rei; + + kfree(ei->entry_attrs); + kfree_const(ei->name); + if (ei->is_events) { + rei = get_root_inode(ei); + kfree(rei); + } else { + kfree(ei); + } +} + /* * eventfs_inode reference count management. * @@ -85,7 +100,6 @@ static void release_ei(struct kref *ref) { struct eventfs_inode *ei = container_of(ref, struct eventfs_inode, kref); const struct eventfs_entry *entry; - struct eventfs_root_inode *rei; WARN_ON_ONCE(!ei->is_freed); @@ -95,14 +109,7 @@ static void release_ei(struct kref *ref) entry->release(entry->name, ei->data); } - kfree(ei->entry_attrs); - kfree_const(ei->name); - if (ei->is_events) { - rei = get_root_inode(ei); - kfree_rcu(rei, ei.rcu); - } else { - kfree_rcu(ei, rcu); - } + call_rcu(&ei->rcu, free_ei_rcu); } static inline void put_ei(struct eventfs_inode *ei)
