Am Montag, dem 22.01.2024 um 15:56 -0800 schrieb Greg Kroah-Hartman:
5.4-stable review patch. If anyone has any objections, please let me know.
From: ZhaoLong Wang wangzhaolong1@huawei.com
[ Upstream commit a43bdc376deab5fff1ceb93dca55bcab8dbdc1d6 ]
If both ftl.ko and gluebi.ko are loaded, the notifier of ftl triggers NULL pointer dereference when trying to access ‘gluebi->desc’ in gluebi_read().
ubi_gluebi_init ubi_register_volume_notifier ubi_enumerate_volumes ubi_notify_all gluebi_notify nb->notifier_call() gluebi_create mtd_device_register mtd_device_parse_register add_mtd_device blktrans_notify_add not->add() ftl_add_mtd tr->add_mtd() scan_header mtd_read mtd_read_oob mtd_read_oob_std gluebi_read mtd->read() gluebi->desc - NULL
Detailed reproduction information available at the Link [1],
In the normal case, obtain gluebi->desc in the gluebi_get_device(), and access gluebi->desc in the gluebi_read(). However, gluebi_get_device() is not executed in advance in the ftl_add_mtd() process, which leads to NULL pointer dereference.
The solution for the gluebi module is to run jffs2 on the UBI volume without considering working with ftl or mtdblock [2]. Therefore, this problem can be avoided by preventing gluebi from creating the mtdblock device after creating mtd partition of the type MTD_UBIVOLUME.
Fixes: 2ba3d76a1e29 ("UBI: make gluebi a separate module") Link: https://bugzilla.kernel.org/show_bug.cgi?id=217992%C2%A0%5B1] Link: https://lore.kernel.org/lkml/441107100.23734.1697904580252.JavaMail.zimbra@n... [2] Signed-off-by: ZhaoLong Wang wangzhaolong1@huawei.com Reviewed-by: Zhihao Cheng chengzhihao1@huawei.com Acked-by: Richard Weinberger richard@nod.at Signed-off-by: Miquel Raynal miquel.raynal@bootlin.com Link: https://lore.kernel.org/linux-mtd/20231220024619.2138625-1-wangzhaolong1@hua... Signed-off-by: Sasha Levin sashal@kernel.org
drivers/mtd/mtd_blkdevs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c index 0c05f77f9b21..dd0d0bf5f57f 100644 --- a/drivers/mtd/mtd_blkdevs.c +++ b/drivers/mtd/mtd_blkdevs.c @@ -533,7 +533,7 @@ static void blktrans_notify_add(struct mtd_info *mtd) { struct mtd_blktrans_ops *tr; - if (mtd->type == MTD_ABSENT) + if (mtd->type == MTD_ABSENT || mtd->type == MTD_UBIVOLUME) return; list_for_each_entry(tr, &blktrans_majors, list) @@ -576,7 +576,7 @@ int register_mtd_blktrans(struct mtd_blktrans_ops *tr) list_add(&tr->list, &blktrans_majors); mtd_for_each_device(mtd) - if (mtd->type != MTD_ABSENT) + if (mtd->type != MTD_ABSENT && mtd->type != MTD_UBIVOLUME) tr->add_mtd(tr, mtd); mutex_unlock(&mtd_table_mutex);
Hi Greg, hi patch-developers,
wait a second. this already went into v5.4.268 but still: Doesn't this break userspace?
According to https://lore.kernel.org/lkml/441107100.23734.1697904580252.JavaMail.zimbra@n... where this solution seems to come from, the behaviour changes: "no mtdblock (hence, also no FTLs) on top of gluebi."
I fell accross this because of an out-of-tree module that does sys_mount() an mtdblock, so I won't complain about my code specifically :) But doesn't it break mounting, say, jffs2 inside an ubi via mtdblock? If so, is this really something that you want to see backported to old kernels?
Or differently put: Has this patch been picked up for old stable kernels by scripts or by a human?
I just want to make sure, and who knows, it might help others too, who would just do a (possibly dangerous?) revert in their trees.
thanks! martin