+ ipc-msgc-fix-percpu_counter-use-after-free.patch added to mm-hotfixes-unstable branch

+ ipc-msgc-fix-percpu_counter-use-after-free.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: ipc/msg.c: fix percpu_counter use after free
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     ipc-msgc-fix-percpu_counter-use-after-free.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/ipc-msgc-fix-percpu_counter-use-after-free.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Andrew Morton <akpm@linux-foundation.org>
Subject: ipc/msg.c: fix percpu_counter use after free
Date: Thu Oct 20 09:19:22 PM PDT 2022

These percpu counters are referenced in free_ipcs->freeque, so destroy
them later.

Fixes: 72d1e611082e ("ipc/msg: mitigate the lock contention with percpu counter")
Reported-by: syzbot+96e659d35b9d6b541152@syzkaller.appspotmail.com
Cc: Jiebin Sun <jiebin.sun@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 ipc/msg.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/ipc/msg.c~ipc-msgc-fix-percpu_counter-use-after-free
+++ a/ipc/msg.c
@@ -1329,11 +1329,11 @@ fail_msg_bytes:
 #ifdef CONFIG_IPC_NS
 void msg_exit_ns(struct ipc_namespace *ns)
 {
-	percpu_counter_destroy(&ns->percpu_msg_bytes);
-	percpu_counter_destroy(&ns->percpu_msg_hdrs);
 	free_ipcs(ns, &msg_ids(ns), freeque);
 	idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
 	rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht);
+	percpu_counter_destroy(&ns->percpu_msg_bytes);
+	percpu_counter_destroy(&ns->percpu_msg_hdrs);
 }
 #endif
 
_

Patches currently in -mm which might be from akpm@linux-foundation.org are

mm-mmapc-__vma_adjust-suppress-unintialized-var-warning.patch
ipc-msgc-fix-percpu_counter-use-after-free.patch
mm-memremap_pages-replace-zone_device_page_init-with-pgmap_request_folios-fix.patch
mm-hugetlb-convert-free_huge_page-to-folios-fix.patch
vmalloc-add-reviewers-for-vmalloc-code-checkpatch-fixes.patch
powerpc-ptrace-user_regset_copyin_ignore-always-returns-0-fix.patch
minmax-sanity-check-constant-bounds-when-clamping-checkpatch-fixes.patch
minmax-sanity-check-constant-bounds-when-clamping-checkpatch-fixes-fix.patch
proc-report-open-files-as-size-in-stat-for-proc-pid-fd-v3-fix.patch