This is a note to let you know that I've just added the patch titled
dm btree remove: assign new_root only when removal succeeds
to the 5.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dm-btree-remove-assign-new_root-only-when-removal-succeeds.patch
and it can be found in the queue-5.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b6e58b5466b2959f83034bead2e2e1395cca8aeb Mon Sep 17 00:00:00 2001
From: Hou Tao <houtao1@xxxxxxxxxx>
Date: Thu, 17 Jun 2021 15:45:47 +0800
Subject: dm btree remove: assign new_root only when removal succeeds
From: Hou Tao <houtao1@xxxxxxxxxx>
commit b6e58b5466b2959f83034bead2e2e1395cca8aeb upstream.
remove_raw() in dm_btree_remove() may fail due to IO read error
(e.g. read the content of origin block fails during shadowing),
and the value of shadow_spine::root is uninitialized, but
the uninitialized value is still assign to new_root in the
end of dm_btree_remove().
For dm-thin, the value of pmd->details_root or pmd->root will become
an uninitialized value, so if trying to read details_info tree again
out-of-bound memory may occur as showed below:
general protection fault, probably for non-canonical address 0x3fdcb14c8d7520
CPU: 4 PID: 515 Comm: dmsetup Not tainted 5.13.0-rc6
Hardware name: QEMU Standard PC
RIP: 0010:metadata_ll_load_ie+0x14/0x30
Call Trace:
sm_metadata_count_is_more_than_one+0xb9/0xe0
dm_tm_shadow_block+0x52/0x1c0
shadow_step+0x59/0xf0
remove_raw+0xb2/0x170
dm_btree_remove+0xf4/0x1c0
dm_pool_delete_thin_device+0xc3/0x140
pool_message+0x218/0x2b0
target_message+0x251/0x290
ctl_ioctl+0x1c4/0x4d0
dm_ctl_ioctl+0xe/0x20
__x64_sys_ioctl+0x7b/0xb0
do_syscall_64+0x40/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
Fixing it by only assign new_root when removal succeeds
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/persistent-data/dm-btree-remove.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/md/persistent-data/dm-btree-remove.c
+++ b/drivers/md/persistent-data/dm-btree-remove.c
@@ -549,7 +549,8 @@ int dm_btree_remove(struct dm_btree_info
delete_at(n, index);
}
- *new_root = shadow_root(&spine);
+ if (!r)
+ *new_root = shadow_root(&spine);
exit_shadow_spine(&spine);
return r;
Patches currently in stable-queue which might be from houtao1@xxxxxxxxxx are
queue-5.12/dm-btree-remove-assign-new_root-only-when-removal-succeeds.patch
queue-5.12/ubifs-fix-races-between-xattr_-set-get-and-listxattr-operations.patch
