ceph: fix directories inode i_blkbits initialization

[ 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@suse.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index a663b67..2ad3f4a 100644 (file)
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -725,7 +725,12 @@ 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) {