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...
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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 Wangwangkefeng.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)