From: Randy Dunlap <rdun...@infradead.org> If the reiserfs mount option's journal name contains a '%' character, it can lead to a WARN_ONCE() in lib/vsprintf.c::format_decode(), saying: "Please remove unsupported %/ in format string." That's OK until panic_on_warn is set, at which point it's dead, Jim.
To placate this situation, check the journal name string for a '%' character and return an error if one is found. Also print a warning (one that won't panic the kernel) about the invalid journal name (e.g.): reiserfs: journal device name is invalid: %/file0 (In this example, the caller app specified the journal device name as "%/file0".) Fixes: https://syzkaller.appspot.com/bug?id=0627d4551fdc39bf1ef5d82cd9eef587047f7718 Reported-by: syzbot+6bd77b88c1977c03f...@syzkaller.appspotmail.com Signed-off-by: Randy Dunlap <rdun...@infradead.org> Cc: sta...@vger.kernel.org # many kernel versions Cc: reiserfs-de...@vger.kernel.org Cc: Alexander Viro <v...@zeniv.linux.org.uk> Cc: Jeff Mahoney <je...@suse.com> Cc: Jan Kara <j...@suse.com> Cc: Frederic Weisbecker <fweis...@gmail.com> Cc: Artem Bityutskiy <dedeki...@gmail.com> Cc: Andrew Morton <a...@linuxfoundation.org> --- fs/reiserfs/super.c | 11 +++++++++++ 1 file changed, 11 insertions(+) --- lnx-416.orig/fs/reiserfs/super.c +++ lnx-416/fs/reiserfs/super.c @@ -1239,6 +1239,8 @@ static int reiserfs_parse_options(struct } if (c == 'j') { + char *badfmt; // jdev_name (arg) cannot contain '%' + if (arg && *arg && jdev_name) { /* Hm, already assigned? */ if (*jdev_name) { @@ -1248,6 +1250,15 @@ static int reiserfs_parse_options(struct "be %s", *jdev_name); return 0; } + + badfmt = strchr(arg, '%'); + if (badfmt) { + printk(KERN_WARNING "reiserfs: " + "journal device name " + "is invalid: %s", + arg); + return 0; + } *jdev_name = arg; } }
