Re: [PATCH AUTOSEL 5.10 16/27] btrfs: tree-checker: check item_size for dev_item
From: Su Yue
Date: Fri Feb 18 2022 - 07:02:21 EST
On Fri 18 Feb 2022 at 11:36, Greg KH <greg@xxxxxxxxx> wrote:
On Wed, Feb 09, 2022 at 01:40:52PM -0500, Sasha Levin wrote:
From: Su Yue <l@xxxxxxxxxx>
[ Upstream commit ea1d1ca4025ac6c075709f549f9aa036b5b6597d ]
Check item size before accessing the device item to avoid out
of bound
access, similar to inode_item check.
Signed-off-by: Su Yue <l@xxxxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/btrfs/tree-checker.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index d4a3a56726aa8..4a5ee516845f7 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -947,6 +947,7 @@ static int check_dev_item(struct
extent_buffer *leaf,
struct btrfs_key *key, int slot)
{
struct btrfs_dev_item *ditem;
+ const u32 item_size = btrfs_item_size(leaf, slot);
if (key->objectid != BTRFS_DEV_ITEMS_OBJECTID) {
dev_item_err(leaf, slot,
@@ -954,6 +955,13 @@ static int check_dev_item(struct
extent_buffer *leaf,
key->objectid,
BTRFS_DEV_ITEMS_OBJECTID);
return -EUCLEAN;
}
+
+ if (unlikely(item_size != sizeof(*ditem))) {
+ dev_item_err(leaf, slot, "invalid item size: has
%u expect %zu",
+ item_size, sizeof(*ditem));
+ return -EUCLEAN;
+ }
+
ditem = btrfs_item_ptr(leaf, slot, struct btrfs_dev_item);
if (btrfs_device_id(leaf, ditem) != key->offset) {
dev_item_err(leaf, slot,
--
2.34.1
This adds a build warning, showing that the backport is not
correct, so
I'll go drop this :(
And the warning is
========================================================================
arch/x86/kernel/head_64.o: warning: objtool: .text+0x5:
unreachable instruction
fs/btrfs/tree-checker.c: In function
\342\200\230check_dev_item\342\200\231:
fs/btrfs/tree-checker.c:950:53: warning: passing argument 2 of
\342\200\230btrfs_item_size\342\200\231 makes pointer from integer
without a cast [-Wint-conversion]
950 | const u32 item_size = btrfs_item_size(leaf, slot);
| ^~~~
| |
| int
In file included from fs/btrfs/tree-checker.c:21:
fs/btrfs/ctree.h:1474:48: note: expected \342\200\230const struct
btrfs_item *\342\200\231 but argument is of type
\342\200\230int\342\200\231
1474 | const type *s)
\
| ~~~~~~~~~~~~^
fs/btrfs/ctree.h:1833:1: note: in expansion of macro
\342\200\230BTRFS_SETGET_FUNCS\342\200\231
1833 | BTRFS_SETGET_FUNCS(item_size, struct btrfs_item, size,
32);
| ^~~~~~~~~~~~~~~~~~
========================================================================
The upstream patchset[1] merged in 5.17-rc1, changed second
parameter
of btrfs_item_size() from btrfs_item * to int directly.
So yes, the backport is wrong.
I'm not familiar with stable backport progress. Should I file a
patch
using btrfs_item *? Or just drop it?
The patch is related to 0c982944af27d131d3b74242f3528169f66950ad
but
I wonder why the 0c98294 is not selected automatically.
Thanks.
[1]:
https://patchwork.kernel.org/project/linux-btrfs/cover/cover.1634842475.git.josef@xxxxxxxxxxxxxx/
--
Su
thanks,
greg k-h