commit d78f3853f831eee46c6dbe726debf3be9e9c0d05 upstream. 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 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> # 5.15.x Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> --- mm/damon/dbgfs.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c index 2741ff79e8e8..f94d19a690df 100644 --- a/mm/damon/dbgfs.c +++ b/mm/damon/dbgfs.c @@ -538,12 +538,14 @@ static ssize_t dbgfs_monitor_on_write(struct file *file, return -EINVAL; } + mutex_lock(&damon_dbgfs_lock); if (!strncmp(kbuf, "on", count)) err = damon_start(dbgfs_ctxs, dbgfs_nr_ctxs); else if (!strncmp(kbuf, "off", count)) err = damon_stop(dbgfs_ctxs, dbgfs_nr_ctxs); else err = -EINVAL; + mutex_unlock(&damon_dbgfs_lock); if (err) ret = err; @@ -596,15 +598,16 @@ static int __init __damon_dbgfs_init(void) 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; @@ -615,6 +618,8 @@ static int __init damon_dbgfs_init(void) pr_err("%s: dbgfs init failed\n", __func__); } +out: + mutex_unlock(&damon_dbgfs_lock); return rc; } -- 2.17.1
