From: SeongJae Park <sj@xxxxxxxxxx> Subject: mm/damon/dbgfs: fix missed use of damon_dbgfs_lock DAMON debugfs is supposed to protect dbgfs_ctxs, dbgfs_nr_ctxs, and dbgfs_dirs using damon_dbgfs_lock. However, some of the code is accessing the variables without the protection. This commit fixes it by protecting all such accesses. Link: https://lkml.kernel.org/r/20211110145758.16558-3-sj@xxxxxxxxxx Fixes: 75c1c2b53c78 ("mm/damon/dbgfs: support multiple contexts") Signed-off-by: SeongJae Park <sj@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/damon/dbgfs.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) --- a/mm/damon/dbgfs.c~mm-damon-dbgfs-fix-missed-use-of-damon_dbgfs_lock +++ a/mm/damon/dbgfs.c @@ -877,12 +877,14 @@ static ssize_t dbgfs_monitor_on_write(st return -EINVAL; } + mutex_lock(&damon_dbgfs_lock); if (!strncmp(kbuf, "on", count)) { int i; for (i = 0; i < dbgfs_nr_ctxs; i++) { if (damon_targets_empty(dbgfs_ctxs[i])) { kfree(kbuf); + mutex_unlock(&damon_dbgfs_lock); return -EINVAL; } } @@ -892,6 +894,7 @@ static ssize_t dbgfs_monitor_on_write(st } else { ret = -EINVAL; } + mutex_unlock(&damon_dbgfs_lock); if (!ret) ret = count; @@ -944,15 +947,16 @@ static int __init __damon_dbgfs_init(voi static int __init damon_dbgfs_init(void) { - int rc; + int rc = -ENOMEM; + mutex_lock(&damon_dbgfs_lock); dbgfs_ctxs = kmalloc(sizeof(*dbgfs_ctxs), GFP_KERNEL); if (!dbgfs_ctxs) - return -ENOMEM; + goto out; dbgfs_ctxs[0] = dbgfs_new_ctx(); if (!dbgfs_ctxs[0]) { kfree(dbgfs_ctxs); - return -ENOMEM; + goto out; } dbgfs_nr_ctxs = 1; @@ -963,6 +967,8 @@ static int __init damon_dbgfs_init(void) pr_err("%s: dbgfs init failed\n", __func__); } +out: + mutex_unlock(&damon_dbgfs_lock); return rc; } _
