md-cache: avoid checking the xattr value buffer with string functions.

xattrs may very well contain binary, non-text data with leading 0
values. Using strcmp for checking empty values is not the appropriate
thing to do: In the best case, it might treat a binary xattr value
starting with 0 from being cached (and hence also from being reported
back with xattr). In the worst case, we might read beyond the end
of a data blob that does contain any zero byte.

We fix this by checking the length of the data blob and checking
the first byte against 0 if the length is one.

Signed-off-by: Guenther Deschner <gd@samba.org>
Pair-Programmed-With: Michael Adam <obnox@samba.org>
Change-Id: If723c465a630b8a37b6be58782a2724df7ac6b11
BUG: 1476324
Reviewed-on: https://review.gluster.org/17910
Reviewed-by: Michael Adam <obnox@samba.org>
Smoke: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Poornima G <pgurusid@redhat.com>
Tested-by: Poornima G <pgurusid@redhat.com>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>

1 files changed, 27 insertions, 0 deletions

diff --git a/tests/bugs/md-cache/bug-1476324.t b/tests/bugs/md-cache/bug-1476324.t
new file mode 100644
index 00000000000..c34f412a15e
--- /dev/null
+++ b/tests/bugs/md-cache/bug-1476324.t
@@ -0,0 +1,27 @@
+#!/bin/bash
+
+. $(dirname $0)/../../include.rc
+. $(dirname $0)/../../volume.rc
+
+cleanup;
+
+TEST glusterd;
+
+TEST $CLI volume create $V0 $H0:$B0/${V0}{1,2,3};
+
+TEST $CLI volume start $V0
+
+TEST $CLI volume set $V0 performance.md-cache-timeout 600
+TEST $CLI volume set $V0 performance.cache-samba-metadata on
+
+TEST glusterfs --volfile-id=/$V0 --volfile-server=$H0 $M0
+
+TEST touch $M0/file1
+
+TEST "setfattr -n user.DOSATTRIB -v 0sAAOW $M0/file1"
+TEST "getfattr -n user.DOSATTRIB $M0/file1 -e base64 | grep -q 0sAAOW"
+
+TEST "setfattr -n user.DOSATTRIB -v 0x00ff $M0/file1"
+TEST "getfattr -n user.DOSATTRIB $M0/file1 -e hex | grep -q 0x00ff"
+
+cleanup;