Merge tag 'mm-nonmm-stable-2022-05-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull misc updates from Andrew Morton:
 "The non-MM patch queue for this merge window.

  Not a lot of material this cycle. Many singleton patches against
  various subsystems. Most notably some maintenance work in ocfs2
  and initramfs"

* tag 'mm-nonmm-stable-2022-05-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (65 commits)
  kcov: update pos before writing pc in trace function
  ocfs2: dlmfs: fix error handling of user_dlm_destroy_lock
  ocfs2: dlmfs: don't clear USER_LOCK_ATTACHED when destroying lock
  fs/ntfs: remove redundant variable idx
  fat: remove time truncations in vfat_create/vfat_mkdir
  fat: report creation time in statx
  fat: ignore ctime updates, and keep ctime identical to mtime in memory
  fat: split fat_truncate_time() into separate functions
  MAINTAINERS: add Muchun as a memcg reviewer
  proc/sysctl: make protected_* world readable
  ia64: mca: drop redundant spinlock initialization
  tty: fix deadlock caused by calling printk() under tty_port->lock
  relay: remove redundant assignment to pointer buf
  fs/ntfs3: validate BOOT sectors_per_clusters
  lib/string_helpers: fix not adding strarray to device's resource list
  kernel/crash_core.c: remove redundant check of ck_cmdline
  ELF, uapi: fixup ELF_ST_TYPE definition
  ipc/mqueue: use get_tree_nodev() in mqueue_get_tree()
  ipc: update semtimedop() to use hrtimer
  ipc/sem: remove redundant assignments
  ...

1 files changed, 12 insertions, 2 deletions

diff --git a/kernel/kcov.c b/kernel/kcov.c
index b3732b210593..e19c84b02452 100644
--- a/kernel/kcov.c
+++ b/kernel/kcov.c
@@ -204,8 +204,16 @@ void notrace __sanitizer_cov_trace_pc(void)
 	/* The first 64-bit word is the number of subsequent PCs. */
 	pos = READ_ONCE(area[0]) + 1;
 	if (likely(pos < t->kcov_size)) {
-		area[pos] = ip;
+		/* Previously we write pc before updating pos. However, some
+		 * early interrupt code could bypass check_kcov_mode() check
+		 * and invoke __sanitizer_cov_trace_pc(). If such interrupt is
+		 * raised between writing pc and updating pos, the pc could be
+		 * overitten by the recursive __sanitizer_cov_trace_pc().
+		 * Update pos before writing pc to avoid such interleaving.
+		 */
 		WRITE_ONCE(area[0], pos);
+		barrier();
+		area[pos] = ip;
 	}
 }
 EXPORT_SYMBOL(__sanitizer_cov_trace_pc);
@@ -236,11 +244,13 @@ static void notrace write_comp_data(u64 type, u64 arg1, u64 arg2, u64 ip)
 	start_index = 1 + count * KCOV_WORDS_PER_CMP;
 	end_pos = (start_index + KCOV_WORDS_PER_CMP) * sizeof(u64);
 	if (likely(end_pos <= max_pos)) {
+		/* See comment in __sanitizer_cov_trace_pc(). */
+		WRITE_ONCE(area[0], count + 1);
+		barrier();
 		area[start_index] = type;
 		area[start_index + 1] = arg1;
 		area[start_index + 2] = arg2;
 		area[start_index + 3] = ip;
-		WRITE_ONCE(area[0], count + 1);
 	}
 }