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Subject[PATCH AUTOSEL 4.9 05/19] ceph: fix directories inode i_blkbits initialization
Date
From: Luis Henriques <lhenriques@suse.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@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>
---
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
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