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@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-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@xxxxxxxxxxxxxxx>' --in-reply-to '16800049118459@xxxxxxxxx' --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@xxxxxxxxx> 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@xxxxxxxxxxxxx Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure") Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> Tested-by: Marco Elver <elver@xxxxxxxxxx> Reviewed-by: Marco Elver <elver@xxxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Jann Horn <jannh@xxxxxxxxxx> Cc: SeongJae Park <sjpark@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> 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; }
