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emacs 27.2 From: Su Yue To: Greg KH Cc: Sasha Levin , linux-kernel@vger.kernel.org, stable@vger.kernel.org, David Sterba , clm@fb.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org Subject: Re: [PATCH AUTOSEL 5.10 16/27] btrfs: tree-checker: check item_size for dev_item Date: Fri, 18 Feb 2022 19:25:20 +0800 In-reply-to: Message-ID: <1r00qtxj.fsf@damenly.su> MIME-Version: 1.0 Content-Type: text/plain; format=flowed X-Virus-Scanned: OK X-ESPOL: +dBm1NUOBk3XhyTBXxmtCA4rzV5EXevl+uWy0xxdmmeDUSOFfksTURS1g21yTGK6vzsX Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 18 Feb 2022 at 11:36, Greg KH wrote: > On Wed, Feb 09, 2022 at 01:40:52PM -0500, Sasha Levin wrote: >> From: Su Yue >> >> [ 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 >> Reviewed-by: David Sterba >> Signed-off-by: David Sterba >> Signed-off-by: Sasha Levin >> --- >> 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@toxicpanda.com/ -- Su > thanks, > > greg k-h