linux-kernel - [PATCH AUTOSEL 4.9 05/19] ceph: fix directories inode i

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Message-Id: <20191001164505.16708-5-sashal@kernel.org>
Date:   Tue,  1 Oct 2019 12:44:51 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Luis Henriques <lhenriques@...e.com>,
        Jeff Layton <jlayton@...nel.org>,
        Ilya Dryomov <idryomov@...il.com>,
        Sasha Levin <sashal@...nel.org>, ceph-devel@...r.kernel.org
Subject: [PATCH AUTOSEL 4.9 05/19] ceph: fix directories inode i_blkbits initialization

From: Luis Henriques <lhenriques@...e.com>

[ Upstream commit 750670341a24cb714e624e0fd7da30900ad93752 ]

When filling an inode with info from the MDS, i_blkbits is being
initialized using fl_stripe_unit, which contains the stripe unit in
bytes.  Unfortunately, this doesn't make sense for directories as they
have fl_stripe_unit set to '0'.  This means that i_blkbits will be set
to 0xff, causing an UBSAN undefined behaviour in i_blocksize():

  UBSAN: Undefined behaviour in ./include/linux/fs.h:731:12
  shift exponent 255 is too large for 32-bit type 'int'

Fix this by initializing i_blkbits to CEPH_BLOCK_SHIFT if fl_stripe_unit
is zero.

Signed-off-by: Luis Henriques <lhenriques@...e.com>
Reviewed-by: Jeff Layton <jlayton@...nel.org>
Signed-off-by: Ilya Dryomov <idryomov@...il.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/ceph/inode.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 339fdf6355df7..7fcddaaca8a5d 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -800,7 +800,12 @@ static int fill_inode(struct inode *inode, struct page *locked_page,
 	ci->i_version = le64_to_cpu(info->version);
 	inode->i_version++;
 	inode->i_rdev = le32_to_cpu(info->rdev);
-	inode->i_blkbits = fls(le32_to_cpu(info->layout.fl_stripe_unit)) - 1;
+	/* directories have fl_stripe_unit set to zero */
+	if (le32_to_cpu(info->layout.fl_stripe_unit))
+		inode->i_blkbits =
+			fls(le32_to_cpu(info->layout.fl_stripe_unit)) - 1;
+	else
+		inode->i_blkbits = CEPH_BLOCK_SHIFT;
 
 	if ((new_version || (new_issued & CEPH_CAP_AUTH_SHARED)) &&
 	    (issued & CEPH_CAP_AUTH_EXCL) == 0) {
-- 
2.20.1