From b4c07bce796833401317519e44075889c5fd4d5f Mon Sep 17 00:00:00 2001 From: Lee Schermerhorn Date: Sun, 15 Jul 2007 23:40:54 -0700 Subject: [PATCH] hugetlbfs: handle empty options string I was seeing a null pointer deref in fs/super.c:vfs_kern_mount(). Some file system get_sb() handler was returning NULL mnt_sb with a non-negative return value. I also noticed a "hugetlbfs: Bad mount option:" message in the log. Turns out that hugetlbfs_parse_options() was not checking for an empty option string after call to strsep(). On failure, hugetlbfs_parse_options() returns 1. hugetlbfs_fill_super() just passed this return code back up the call stack where vfs_kern_mount() missed the error and proceeded with a NULL mnt_sb. Apparently introduced by patch: hugetlbfs-use-lib-parser-fix-docs.patch The problem was exposed by this line in my fstab: none /huge hugetlbfs defaults 0 0 It can also be demonstrated by invoking mount of hugetlbfs directly with no options or a bogus option. This patch: 1) adds the check for empty option to hugetlbfs_parse_options(), 2) enhances the error message to bracket any unrecognized option with quotes , 3) modifies hugetlbfs_parse_options() to return -EINVAL on any unrecognized option, 4) adds a BUG_ON() to vfs_kern_mount() to catch any get_sb() handler that returns a NULL mnt->mnt_sb with a return value >= 0. Signed-off-by: Lee Schermerhorn Acked-by: Randy Dunlap Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/hugetlbfs/inode.c | 8 +++++--- fs/super.c | 1 + 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 711b801fbcdf..d145cb79c30a 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -621,6 +621,8 @@ hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig) while ((p = strsep(&options, ",")) != NULL) { int token; + if (!*p) + continue; token = match_token(p, tokens, args); switch (token) { @@ -665,8 +667,9 @@ hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig) break; default: - printk(KERN_ERR "hugetlbfs: Bad mount option: %s\n", p); - return 1; + printk(KERN_ERR "hugetlbfs: Bad mount option: \"%s\"\n", + p); + return -EINVAL; break; } } @@ -693,7 +696,6 @@ hugetlbfs_fill_super(struct super_block *sb, void *data, int silent) config.gid = current->fsgid; config.mode = 0755; ret = hugetlbfs_parse_options(data, &config); - if (ret) return ret; diff --git a/fs/super.c b/fs/super.c index 5260d620c555..fc8ebedc6bed 100644 --- a/fs/super.c +++ b/fs/super.c @@ -884,6 +884,7 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void error = type->get_sb(type, flags, name, data, mnt); if (error < 0) goto out_free_secdata; + BUG_ON(!mnt->mnt_sb); error = security_sb_kern_mount(mnt->mnt_sb, secdata); if (error) -- 2.30.2