From af4e36318edb848fcc0a8d5f75000ca00cdc7595 Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Fri, 13 Aug 2010 12:42:24 +0900 Subject: [PATCH] nilfs2: fix list corruption after ifile creation failure If nilfs_attach_checkpoint() gets a memory allocation failure during creation of ifile, it will return without removing nilfs_sb_info struct from ns_supers list. When a concurrently mounted snapshot is unmounted or another new snapshot is mounted after that, this causes kernel oops as below: > BUG: unable to handle kernel NULL pointer dereference at (null) > IP: [] nilfs_find_sbinfo+0x74/0xa4 [nilfs2] > *pde = 00000000 > Oops: 0000 [#1] SMP > Call Trace: > [] ? nilfs_get_sb+0x165/0x532 [nilfs2] > [] ? ida_get_new_above+0x16d/0x187 > [] ? alloc_vfsmnt+0x7e/0x10a > [] ? kstrdup+0x2c/0x40 > [] ? vfs_kern_mount+0x96/0x14e > [] ? do_kern_mount+0x32/0xbd > [] ? do_mount+0x642/0x6a1 > [] ? do_page_fault+0x0/0x2d1 > [] ? copy_mount_options+0x80/0xe2 > [] ? strndup_user+0x48/0x67 > [] ? sys_mount+0x61/0x90 > [] ? sysenter_do_call+0x12/0x22 This fixes the problem. Signed-off-by: Ryusuke Konishi Tested-by: Ryusuke Konishi Cc: stable@kernel.org --- fs/nilfs2/super.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c index 1fa86b9df73..bee60c04109 100644 --- a/fs/nilfs2/super.c +++ b/fs/nilfs2/super.c @@ -400,9 +400,10 @@ int nilfs_attach_checkpoint(struct nilfs_sb_info *sbi, __u64 cno) list_add(&sbi->s_list, &nilfs->ns_supers); up_write(&nilfs->ns_super_sem); + err = -ENOMEM; sbi->s_ifile = nilfs_ifile_new(sbi, nilfs->ns_inode_size); if (!sbi->s_ifile) - return -ENOMEM; + goto delist; down_read(&nilfs->ns_segctor_sem); err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, cno, 0, &raw_cp, @@ -433,6 +434,7 @@ int nilfs_attach_checkpoint(struct nilfs_sb_info *sbi, __u64 cno) nilfs_mdt_destroy(sbi->s_ifile); sbi->s_ifile = NULL; + delist: down_write(&nilfs->ns_super_sem); list_del_init(&sbi->s_list); up_write(&nilfs->ns_super_sem); -- 2.20.1