From 0ca7a5b9ac5d301845dd6382ff25a699b6263a81 Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Fri, 21 Jan 2011 16:40:31 +0900 Subject: [PATCH] nilfs2: fix crash after one superblock became unavailable Fixes the following kernel oops in nilfs_setup_super() which could arise if one of two super-blocks is unavailable. > BUG: unable to handle kernel NULL pointer dereference at (null) > Pid: 3529, comm: mount.nilfs2 Not tainted 2.6.37 #1 / > EIP: 0060:[] EFLAGS: 00010202 CPU: 3 > EIP is at memcpy+0xc/0x1b > Call Trace: > [] ? nilfs_setup_super+0x6c/0xa5 [nilfs2] > [] ? nilfs_get_root_dentry+0x81/0xcb [nilfs2] > [] ? nilfs_mount+0x4f9/0x62c [nilfs2] > [] ? kstrdup+0x36/0x3f > [] ? nilfs_mount+0x0/0x62c [nilfs2] > [] ? vfs_kern_mount+0x4d/0x12c > [] ? get_fs_type+0x76/0x8f > [] ? do_kern_mount+0x33/0xbf > [] ? do_mount+0x2ed/0x714 > [] ? copy_mount_options+0x28/0xfc > [] ? sys_mount+0x72/0xaf > [] ? syscall_call+0x7/0xb Reported-by: Wakko Warner Signed-off-by: Ryusuke Konishi Tested-by: Wakko Warner Cc: stable [2.6.37, 2.6.36] LKML-Reference: <20110121024918.GA29598@animx.eu.org> --- fs/nilfs2/super.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c index 0994f6a76c07..58fd707174e1 100644 --- a/fs/nilfs2/super.c +++ b/fs/nilfs2/super.c @@ -704,7 +704,8 @@ skip_mount_setup: sbp[0]->s_state = cpu_to_le16(le16_to_cpu(sbp[0]->s_state) & ~NILFS_VALID_FS); /* synchronize sbp[1] with sbp[0] */ - memcpy(sbp[1], sbp[0], nilfs->ns_sbsize); + if (sbp[1]) + memcpy(sbp[1], sbp[0], nilfs->ns_sbsize); return nilfs_commit_super(sbi, NILFS_SB_COMMIT_ALL); }