From: Xiaomeng Tong <xiam0nd.tong@gmail.com> stable inclusion from stable-v5.10.121 commit b2b01444228d59ba62b75286c84cea40bb064c64 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5L6CQ Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 64c54d9244a4efe9bc6e9c98e13c4bbb8bb39083 upstream. The bug is here: if (!rdev || rdev->desc_nr != nr) { The list iterator value 'rdev' will *always* be set and non-NULL by rdev_for_each_rcu(), so it is incorrect to assume that the iterator value will be NULL if the list is empty or no element found (In fact, it will be a bogus pointer to an invalid struct object containing the HEAD). Otherwise it will bypass the check and lead to invalid memory access passing the check. To fix the bug, use a new variable 'iter' as the list iterator, while using the original variable 'pdev' as a dedicated pointer to point to the found element. Cc: stable@vger.kernel.org Fixes: 70bcecdb1534 ("md-cluster: Improve md_reload_sb to be less error prone") Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com> Signed-off-by: Song Liu <song@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Acked-by: Xie XiuQi <xiexiuqi@huawei.com> --- drivers/md/md.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 556c136ce743..2ecd4a782203 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -9763,16 +9763,18 @@ static int read_rdev(struct mddev *mddev, struct md_rdev *rdev) void md_reload_sb(struct mddev *mddev, int nr) { - struct md_rdev *rdev; + struct md_rdev *rdev = NULL, *iter; int err; /* Find the rdev */ - rdev_for_each_rcu(rdev, mddev) { - if (rdev->desc_nr == nr) + rdev_for_each_rcu(iter, mddev) { + if (iter->desc_nr == nr) { + rdev = iter; break; + } } - if (!rdev || rdev->desc_nr != nr) { + if (!rdev) { pr_warn("%s: %d Could not find rdev with nr %d\n", __func__, __LINE__, nr); return; } -- 2.20.1