Searched hist:"7727 ae52" (Results 1 – 2 of 2) sorted by relevance
| /openbmc/linux/fs/ext4/ |
| H A D | block_validity.c | 7727ae52 Wed Aug 28 10:13:24 CDT 2019 zhangyi (F) <yi.zhang@huawei.com> ext4: fix potential use after free after remounting with noblock_validity
Remount process will release system zone which was allocated before if
"noblock_validity" is specified. If we mount an ext4 file system to two
mountpoints with default mount options, and then remount one of them
with "noblock_validity", it may trigger a use after free problem when
someone accessing the other one.
# mount /dev/sda foo
# mount /dev/sda bar
User access mountpoint "foo" | Remount mountpoint "bar"
|
ext4_map_blocks() | ext4_remount()
check_block_validity() | ext4_setup_system_zone()
ext4_data_block_valid() | ext4_release_system_zone()
| free system_blks rb nodes
access system_blks rb nodes |
trigger use after free |
This problem can also be reproduced by one mountpint, At the same time,
add_system_zone() can get called during remount as well so there can be
racing ext4_data_block_valid() reading the rbtree at the same time.
This patch add RCU to protect system zone from releasing or building
when doing a remount which inverse current "noblock_validity" mount
option. It assign the rbtree after the whole tree was complete and
do actual freeing after rcu grace period, avoid any intermediate state.
Reported-by: syzbot+1e470567330b7ad711d5@syzkaller.appspotmail.com
Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
7727ae52 Wed Aug 28 10:13:24 CDT 2019 zhangyi (F) <yi.zhang@huawei.com> ext4: fix potential use after free after remounting with noblock_validity
Remount process will release system zone which was allocated before if
"noblock_validity" is specified. If we mount an ext4 file system to two
mountpoints with default mount options, and then remount one of them
with "noblock_validity", it may trigger a use after free problem when
someone accessing the other one.
# mount /dev/sda foo
# mount /dev/sda bar
User access mountpoint "foo" | Remount mountpoint "bar"
|
ext4_map_blocks() | ext4_remount()
check_block_validity() | ext4_setup_system_zone()
ext4_data_block_valid() | ext4_release_system_zone()
| free system_blks rb nodes
access system_blks rb nodes |
trigger use after free |
This problem can also be reproduced by one mountpint, At the same time,
add_system_zone() can get called during remount as well so there can be
racing ext4_data_block_valid() reading the rbtree at the same time.
This patch add RCU to protect system zone from releasing or building
when doing a remount which inverse current "noblock_validity" mount
option. It assign the rbtree after the whole tree was complete and
do actual freeing after rcu grace period, avoid any intermediate state.
Reported-by: syzbot+1e470567330b7ad711d5@syzkaller.appspotmail.com
Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
|
| H A D | ext4.h | 7727ae52 Wed Aug 28 10:13:24 CDT 2019 zhangyi (F) <yi.zhang@huawei.com> ext4: fix potential use after free after remounting with noblock_validity
Remount process will release system zone which was allocated before if
"noblock_validity" is specified. If we mount an ext4 file system to two
mountpoints with default mount options, and then remount one of them
with "noblock_validity", it may trigger a use after free problem when
someone accessing the other one.
# mount /dev/sda foo
# mount /dev/sda bar
User access mountpoint "foo" | Remount mountpoint "bar"
|
ext4_map_blocks() | ext4_remount()
check_block_validity() | ext4_setup_system_zone()
ext4_data_block_valid() | ext4_release_system_zone()
| free system_blks rb nodes
access system_blks rb nodes |
trigger use after free |
This problem can also be reproduced by one mountpint, At the same time,
add_system_zone() can get called during remount as well so there can be
racing ext4_data_block_valid() reading the rbtree at the same time.
This patch add RCU to protect system zone from releasing or building
when doing a remount which inverse current "noblock_validity" mount
option. It assign the rbtree after the whole tree was complete and
do actual freeing after rcu grace period, avoid any intermediate state.
Reported-by: syzbot+1e470567330b7ad711d5@syzkaller.appspotmail.com
Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
7727ae52 Wed Aug 28 10:13:24 CDT 2019 zhangyi (F) <yi.zhang@huawei.com> ext4: fix potential use after free after remounting with noblock_validity
Remount process will release system zone which was allocated before if
"noblock_validity" is specified. If we mount an ext4 file system to two
mountpoints with default mount options, and then remount one of them
with "noblock_validity", it may trigger a use after free problem when
someone accessing the other one.
# mount /dev/sda foo
# mount /dev/sda bar
User access mountpoint "foo" | Remount mountpoint "bar"
|
ext4_map_blocks() | ext4_remount()
check_block_validity() | ext4_setup_system_zone()
ext4_data_block_valid() | ext4_release_system_zone()
| free system_blks rb nodes
access system_blks rb nodes |
trigger use after free |
This problem can also be reproduced by one mountpint, At the same time,
add_system_zone() can get called during remount as well so there can be
racing ext4_data_block_valid() reading the rbtree at the same time.
This patch add RCU to protect system zone from releasing or building
when doing a remount which inverse current "noblock_validity" mount
option. It assign the rbtree after the whole tree was complete and
do actual freeing after rcu grace period, avoid any intermediate state.
Reported-by: syzbot+1e470567330b7ad711d5@syzkaller.appspotmail.com
Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
|