From: SeongJae Park <sj@kernel.org> mainline inclusion from mainline-v5.16-rc7 commit 34796417964b8d0aef45a99cf6c2d20cebe33733 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I4RTX9 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- DAMON debugfs interface iterates current monitoring targets in 'dbgfs_target_ids_read()' while holding the corresponding 'kdamond_lock'. However, it also destructs the monitoring targets in 'dbgfs_before_terminate()' without holding the lock. This can result in a use_after_free bug. This commit avoids the race by protecting the destruction with the corresponding 'kdamond_lock'. Link: https://lkml.kernel.org/r/20211221094447.2241-1-sj@kernel.org Reported-by: Sangwoo Bae <sangwoob@amazon.com> Fixes: 4bc05954d007 ("mm/damon: implement a debugfs-based user space interface") Signed-off-by: SeongJae Park <sj@kernel.org> Cc: <stable@vger.kernel.org> [5.15.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> (cherry picked from commit 34796417964b8d0aef45a99cf6c2d20cebe33733) Signed-off-by: Yue Zou <zouyue3@huawei.com> Reviewed-by: Kefeng Wang<wangkefeng.wang@huawei.com> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> --- mm/damon/dbgfs.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c index 1efac0022e9a..4fbd729edc9e 100644 --- a/mm/damon/dbgfs.c +++ b/mm/damon/dbgfs.c @@ -650,10 +650,12 @@ static void dbgfs_before_terminate(struct damon_ctx *ctx) if (!targetid_is_pid(ctx)) return; + mutex_lock(&ctx->kdamond_lock); damon_for_each_target_safe(t, next, ctx) { put_pid((struct pid *)t->id); damon_destroy_target(t); } + mutex_unlock(&ctx->kdamond_lock); } static struct damon_ctx *dbgfs_new_ctx(void) -- 2.20.1