[Cluster-devel] [PATCH AUTOSEL 5.4 02/13] gfs2: Switch from strlcpy to strscpy

[Cluster-devel] [PATCH AUTOSEL 5.4 02/13] gfs2: Switch from strlcpy to strscpy

[Sasha Levin]

From: Andreas Gruenbacher <agruenba@redhat.com>

[ Upstream commit 204c0300c4e99707e9fb6e57840aa1127060e63f ]

Switch from strlcpy to strscpy and make sure that @count is the size of
the smaller of the source and destination buffers.  This prevents
reading beyond the end of the source buffer when the source string isn't
null terminated.

Found by a modified version of syzkaller.

Suggested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/gfs2/ops_fstype.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index 29b27d769860..2841134f7812 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -377,8 +377,10 @@ static int init_names(struct gfs2_sbd *sdp, int silent)
 	if (!table[0])
 		table = sdp->sd_vfs->s_id;
 
-	strlcpy(sdp->sd_proto_name, proto, GFS2_FSNAME_LEN);
-	strlcpy(sdp->sd_table_name, table, GFS2_FSNAME_LEN);
+	BUILD_BUG_ON(GFS2_LOCKNAME_LEN > GFS2_FSNAME_LEN);
+
+	strscpy(sdp->sd_proto_name, proto, GFS2_LOCKNAME_LEN);
+	strscpy(sdp->sd_table_name, table, GFS2_LOCKNAME_LEN);
 
 	table = sdp->sd_table_name;
 	while ((table = strchr(table, '/')))
@@ -1349,13 +1351,13 @@ static int gfs2_parse_param(struct fs_context *fc, struct fs_parameter *param)
 
 	switch (o) {
 	case Opt_lockproto:
-		strlcpy(args->ar_lockproto, param->string, GFS2_LOCKNAME_LEN);
+		strscpy(args->ar_lockproto, param->string, GFS2_LOCKNAME_LEN);
 		break;
 	case Opt_locktable:
-		strlcpy(args->ar_locktable, param->string, GFS2_LOCKNAME_LEN);
+		strscpy(args->ar_locktable, param->string, GFS2_LOCKNAME_LEN);
 		break;
 	case Opt_hostdata:
-		strlcpy(args->ar_hostdata, param->string, GFS2_LOCKNAME_LEN);
+		strscpy(args->ar_hostdata, param->string, GFS2_LOCKNAME_LEN);
 		break;
 	case Opt_spectator:
 		args->ar_spectator = 1;
-- 
2.35.1

[Cluster-devel] [PATCH AUTOSEL 5.4 06/13] gfs2: Check sb_bsize_shift after reading superblock

[Sasha Levin]

From: Andrew Price <anprice@redhat.com>

[ Upstream commit 670f8ce56dd0632dc29a0322e188cc73ce3c6b92 ]

Fuzzers like to scribble over sb_bsize_shift but in reality it's very
unlikely that this field would be corrupted on its own. Nevertheless it
should be checked to avoid the possibility of messy mount errors due to
bad calculations. It's always a fixed value based on the block size so
we can just check that it's the expected value.

Tested with:

    mkfs.gfs2 -O -p lock_nolock /dev/vdb
    for i in 0 -1 64 65 32 33; do
        gfs2_edit -p sb field sb_bsize_shift $i /dev/vdb
        mount /dev/vdb /mnt/test && umount /mnt/test
    done

Before this patch we get a withdraw after

[   76.413681] gfs2: fsid=loop0.0: fatal: invalid metadata block
[   76.413681]   bh = 19 (type: exp=5, found=4)
[   76.413681]   function = gfs2_meta_buffer, file = fs/gfs2/meta_io.c, line = 492

and with UBSAN configured we also get complaints like

[   76.373395] UBSAN: shift-out-of-bounds in fs/gfs2/ops_fstype.c:295:19
[   76.373815] shift exponent 4294967287 is too large for 64-bit type 'long unsigned int'

After the patch, these complaints don't appear, mount fails immediately
and we get an explanation in dmesg.

Reported-by: syzbot+dcf33a7aae997956fe06 at syzkaller.appspotmail.com
Signed-off-by: Andrew Price <anprice@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/gfs2/ops_fstype.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index 2841134f7812..2112ff7a0172 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -180,7 +180,10 @@ static int gfs2_check_sb(struct gfs2_sbd *sdp, int silent)
 		pr_warn("Invalid superblock size\n");
 		return -EINVAL;
 	}
-
+	if (sb->sb_bsize_shift != ffs(sb->sb_bsize) - 1) {
+		pr_warn("Invalid block size shift\n");
+		return -EINVAL;
+	}
 	return 0;
 }
 
-- 
2.35.1