On Tue, Mar 28, 2023 at 09:02:27PM +0800, Muchun Song wrote:

On 2023/3/28 20:01, gregkh@linuxfoundation.org wrote:

...

The patch below does not apply to the 5.15-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@vger.kernel.org.

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-5.15.y git checkout FETCH_HEAD git cherry-pick -x 1c86a188e03156223a34d09ce290b49bd4dd0403 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '16800049118459@kroah.com' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

1c86a188e031 ("mm: kfence: fix using kfence_metadata without initialization in show_object()") b33f778bba5e ("kfence: alloc kfence_pool after system startup") 698361bca2d5 ("kfence: allow re-enabling KFENCE after system startup") 07e8481d3c38 ("kfence: always use static branches to guard kfence_alloc()") 08f6b10630f2 ("kfence: limit currently covered allocations when pool nearly full") a9ab52bbcb52 ("kfence: move saving stack trace of allocations into __kfence_alloc()") 9a19aeb56650 ("kfence: count unexpectedly skipped allocations")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 1c86a188e03156223a34d09ce290b49bd4dd0403 Mon Sep 17 00:00:00 2001 From: Muchun Song muchun.song@linux.dev Date: Wed, 15 Mar 2023 11:44:41 +0800 Subject: [PATCH] mm: kfence: fix using kfence_metadata without initialization in show_object()

The variable kfence_metadata is initialized in kfence_init_pool(), then, it is not initialized if kfence is disabled after booting. In this case, kfence_metadata will be used (e.g. ->lock and ->state fields) without initialization when reading /sys/kernel/debug/kfence/objects. There will be a warning if you enable CONFIG_DEBUG_SPINLOCK. Fix it by creating debugfs files when necessary.

Link: https://lkml.kernel.org/r/20230315034441.44321-1-songmuchun@bytedance.com Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure") Signed-off-by: Muchun Song songmuchun@bytedance.com Tested-by: Marco Elver elver@google.com Reviewed-by: Marco Elver elver@google.com Cc: Alexander Potapenko glider@google.com Cc: Dmitry Vyukov dvyukov@google.com Cc: Jann Horn jannh@google.com Cc: SeongJae Park sjpark@amazon.de Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org

diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 5349c37a5dac..79c94ee55f97 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -726,10 +726,14 @@ static const struct seq_operations objects_sops = { }; DEFINE_SEQ_ATTRIBUTE(objects); -static int __init kfence_debugfs_init(void) +static int kfence_debugfs_init(void) {

• struct dentry *kfence_dir = debugfs_create_dir("kfence", NULL);

• struct dentry *kfence_dir;
• if (!READ_ONCE(kfence_enabled))

• return 0;
  

• kfence_dir = debugfs_create_dir("kfence", NULL); debugfs_create_file("stats", 0444, kfence_dir, NULL, &stats_fops); debugfs_create_file("objects", 0400, kfence_dir, NULL, &objects_fops); return 0;

@@ -883,6 +887,8 @@ static int kfence_init_late(void) } kfence_init_enable();

• kfence_debugfs_init();
• return 0; }

I have implemented a following patch based on v5.15 branch.

From ba26f344fa3e477456a3cc60488a7b8e5af0e88d Mon Sep 17 00:00:00 2001 From: Muchun Song songmuchun@bytedance.com Date: Wed, 15 Mar 2023 11:44:41 +0800 Subject: [PATCH] mm: kfence: fix using kfence_metadata without initialization  in show_object()

The variable kfence_metadata is initialized in kfence_init_pool(), then, it is not initialized if kfence is disabled after booting.  In this case, kfence_metadata will be used (e.g.  ->lock and ->state fields) without initialization when reading /sys/kernel/debug/kfence/objects.  There will be a warning if you enable CONFIG_DEBUG_SPINLOCK.  Fix it by creating debugfs files when necessary.

Link: https://lkml.kernel.org/r/20230315034441.44321-1-songmuchun@bytedance.com Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure") Signed-off-by: Muchun Song songmuchun@bytedance.com Tested-by: Marco Elver elver@google.com Reviewed-by: Marco Elver elver@google.com Cc: Alexander Potapenko glider@google.com Cc: Dmitry Vyukov dvyukov@google.com Cc: Jann Horn jannh@google.com Cc: SeongJae Park sjpark@amazon.de Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org

---

mm/kfence/core.c | 8 ++++++--  1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 39a6c434e355..573f34e6af0b 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -678,10 +678,14 @@ static const struct file_operations objects_fops = {      .release = seq_release,  };

Patch is corrupted with the whitespace eaten by your email client. Can you resend this in a format that it can be applied?

thanks,

greg k-h

On Tue, Mar 28, 2023 at 09:27:54PM +0800, Muchun Song wrote:

...

On Mar 28, 2023, at 21:19, Greg KH gregkh@linuxfoundation.org wrote:

On Tue, Mar 28, 2023 at 09:02:27PM +0800, Muchun Song wrote:

...

On 2023/3/28 20:01, gregkh@linuxfoundation.org wrote:

...

The patch below does not apply to the 5.15-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@vger.kernel.org.

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-5.15.y git checkout FETCH_HEAD git cherry-pick -x 1c86a188e03156223a34d09ce290b49bd4dd0403 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '16800049118459@kroah.com' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

1c86a188e031 ("mm: kfence: fix using kfence_metadata without initialization in show_object()") b33f778bba5e ("kfence: alloc kfence_pool after system startup") 698361bca2d5 ("kfence: allow re-enabling KFENCE after system startup") 07e8481d3c38 ("kfence: always use static branches to guard kfence_alloc()") 08f6b10630f2 ("kfence: limit currently covered allocations when pool nearly full") a9ab52bbcb52 ("kfence: move saving stack trace of allocations into __kfence_alloc()") 9a19aeb56650 ("kfence: count unexpectedly skipped allocations")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 1c86a188e03156223a34d09ce290b49bd4dd0403 Mon Sep 17 00:00:00 2001 From: Muchun Song muchun.song@linux.dev Date: Wed, 15 Mar 2023 11:44:41 +0800 Subject: [PATCH] mm: kfence: fix using kfence_metadata without initialization in show_object()

The variable kfence_metadata is initialized in kfence_init_pool(), then, it is not initialized if kfence is disabled after booting. In this case, kfence_metadata will be used (e.g. ->lock and ->state fields) without initialization when reading /sys/kernel/debug/kfence/objects. There will be a warning if you enable CONFIG_DEBUG_SPINLOCK. Fix it by creating debugfs files when necessary.

Link: https://lkml.kernel.org/r/20230315034441.44321-1-songmuchun@bytedance.com Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure") Signed-off-by: Muchun Song songmuchun@bytedance.com Tested-by: Marco Elver elver@google.com Reviewed-by: Marco Elver elver@google.com Cc: Alexander Potapenko glider@google.com Cc: Dmitry Vyukov dvyukov@google.com Cc: Jann Horn jannh@google.com Cc: SeongJae Park sjpark@amazon.de Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org

diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 5349c37a5dac..79c94ee55f97 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -726,10 +726,14 @@ static const struct seq_operations objects_sops = { }; DEFINE_SEQ_ATTRIBUTE(objects); -static int __init kfence_debugfs_init(void) +static int kfence_debugfs_init(void) {

• struct dentry *kfence_dir = debugfs_create_dir("kfence", NULL);

• struct dentry *kfence_dir;
• if (!READ_ONCE(kfence_enabled))
• return 0;
• kfence_dir = debugfs_create_dir("kfence", NULL); debugfs_create_file("stats", 0444, kfence_dir, NULL, &stats_fops); debugfs_create_file("objects", 0400, kfence_dir, NULL, &objects_fops); return 0;

@@ -883,6 +887,8 @@ static int kfence_init_late(void) } kfence_init_enable();

• kfence_debugfs_init();
• return 0;

}

I have implemented a following patch based on v5.15 branch.

From ba26f344fa3e477456a3cc60488a7b8e5af0e88d Mon Sep 17 00:00:00 2001 From: Muchun Song songmuchun@bytedance.com Date: Wed, 15 Mar 2023 11:44:41 +0800 Subject: [PATCH] mm: kfence: fix using kfence_metadata without initialization in show_object()

The variable kfence_metadata is initialized in kfence_init_pool(), then, it is not initialized if kfence is disabled after booting. In this case, kfence_metadata will be used (e.g. ->lock and ->state fields) without initialization when reading /sys/kernel/debug/kfence/objects. There will be a warning if you enable CONFIG_DEBUG_SPINLOCK. Fix it by creating debugfs files when necessary.

Link: https://lkml.kernel.org/r/20230315034441.44321-1-songmuchun@bytedance.com Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure") Signed-off-by: Muchun Song songmuchun@bytedance.com Tested-by: Marco Elver elver@google.com Reviewed-by: Marco Elver elver@google.com Cc: Alexander Potapenko glider@google.com Cc: Dmitry Vyukov dvyukov@google.com Cc: Jann Horn jannh@google.com Cc: SeongJae Park sjpark@amazon.de Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org

---

mm/kfence/core.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 39a6c434e355..573f34e6af0b 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -678,10 +678,14 @@ static const struct file_operations objects_fops = { .release = seq_release, };

Patch is corrupted with the whitespace eaten by your email client. Can you resend this in a format that it can be applied?

I attach it here. Could you apply it? Thanks.

That worked, thanks!