From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Valentin Vidic Date: Mon, 27 Sep 2021 17:44:59 +0200 Subject: [PATCH] ocfs2: mount fails with buffer overflow in strlen Starting with kernel v5.11 mouting an ocfs2 filesystem with either o2cb or pcmk cluster stack fails with the trace below. Problem seems to be that strings for cluster stack and cluster name are not guaranteed to be null terminated in the disk representation, while strlcpy assumes that the source string is always null terminated. This causes a read outside of the source string triggering the buffer overflow detection. detected buffer overflow in strlen ------------[ cut here ]------------ kernel BUG at lib/string.c:1149! invalid opcode: 0000 [#1] SMP PTI CPU: 1 PID: 910 Comm: mount.ocfs2 Not tainted 5.14.0-1-amd64 #1 Debian 5.14.6-2 RIP: 0010:fortify_panic+0xf/0x11 ... Call Trace: ocfs2_initialize_super.isra.0.cold+0xc/0x18 [ocfs2] ocfs2_fill_super+0x359/0x19b0 [ocfs2] mount_bdev+0x185/0x1b0 ? ocfs2_remount+0x440/0x440 [ocfs2] legacy_get_tree+0x27/0x40 vfs_get_tree+0x25/0xb0 path_mount+0x454/0xa20 __x64_sys_mount+0x103/0x140 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae Signed-off-by: Valentin Vidic Signed-off-by: Thomas Lamprecht --- fs/ocfs2/super.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c index c86bd4e60e20..1dea535224df 100644 --- a/fs/ocfs2/super.c +++ b/fs/ocfs2/super.c @@ -2169,9 +2169,10 @@ static int ocfs2_initialize_super(struct super_block *sb, if (ocfs2_clusterinfo_valid(osb)) { osb->osb_stackflags = OCFS2_RAW_SB(di)->s_cluster_info.ci_stackflags; - strlcpy(osb->osb_cluster_stack, + memcpy(osb->osb_cluster_stack, OCFS2_RAW_SB(di)->s_cluster_info.ci_stack, - OCFS2_STACK_LABEL_LEN + 1); + OCFS2_STACK_LABEL_LEN); + osb->osb_cluster_stack[OCFS2_STACK_LABEL_LEN] = '\0'; if (strlen(osb->osb_cluster_stack) != OCFS2_STACK_LABEL_LEN) { mlog(ML_ERROR, "couldn't mount because of an invalid " @@ -2180,9 +2181,10 @@ static int ocfs2_initialize_super(struct super_block *sb, status = -EINVAL; goto bail; } - strlcpy(osb->osb_cluster_name, + memcpy(osb->osb_cluster_name, OCFS2_RAW_SB(di)->s_cluster_info.ci_cluster, - OCFS2_CLUSTER_NAME_LEN + 1); + OCFS2_CLUSTER_NAME_LEN); + osb->osb_cluster_name[OCFS2_CLUSTER_NAME_LEN] = '\0'; } else { /* The empty string is identical with classic tools that * don't know about s_cluster_info. */