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authorLee Schermerhorn <Lee.Schermerhorn@hp.com>2007-07-15 23:40:54 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-16 09:05:46 -0700
commitb4c07bce796833401317519e44075889c5fd4d5f (patch)
tree569448b0cc6e0eb1516e38c98bc770ad73308880 /fs/super.c
parente73a75fa7f062b52d015f1c961685dcaac57f710 (diff)
downloadlwn-b4c07bce796833401317519e44075889c5fd4d5f.tar.gz
lwn-b4c07bce796833401317519e44075889c5fd4d5f.zip
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 <lee.schermerhorn@hp.com> Acked-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/super.c')
-rw-r--r--fs/super.c1
1 files changed, 1 insertions, 0 deletions
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)