Syzbot report a task hung in vcs_open. When rec_len too small in nilfs_check_folio, it can result in a huge flood of messages being sent to the console. It eventually caused tty to hung when retrieving the console_lock(). Reported-by: syzbot+8a192e8d090fa9a31135@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=8a192e8d090fa9a31135 Signed-off-by: Lizhi Xu <lizhi.xu@xxxxxxxxxxxxx> --- fs/nilfs2/dir.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) diff --git a/fs/nilfs2/dir.c b/fs/nilfs2/dir.c index fe5b1a30c509..0a89dda75414 100644 --- a/fs/nilfs2/dir.c +++ b/fs/nilfs2/dir.c @@ -32,6 +32,7 @@ #include <linux/pagemap.h> #include "nilfs.h" #include "page.h" +#include <linux/ratelimit.h> static inline unsigned int nilfs_rec_len_from_disk(__le16 dlen) { @@ -115,6 +116,7 @@ static bool nilfs_check_folio(struct folio *folio, char *kaddr) size_t limit = folio_size(folio); struct nilfs_dir_entry *p; char *error; + static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL * 5, 1); if (dir->i_size < folio_pos(folio) + limit) { limit = dir->i_size - folio_pos(folio); @@ -148,9 +150,11 @@ static bool nilfs_check_folio(struct folio *folio, char *kaddr) /* Too bad, we had an error */ Ebadsize: - nilfs_error(sb, - "size of directory #%lu is not a multiple of chunk size", - dir->i_ino); + if (__ratelimit(&rs)) { + nilfs_error(sb, + "size of directory #%lu is not a multiple of chunk size", + dir->i_ino); + } goto fail; Eshort: error = "rec_len is smaller than minimal"; @@ -167,18 +171,22 @@ static bool nilfs_check_folio(struct folio *folio, char *kaddr) Einumber: error = "disallowed inode number"; bad_entry: - nilfs_error(sb, + if (__ratelimit(&rs)) { + nilfs_error(sb, "bad entry in directory #%lu: %s - offset=%lu, inode=%lu, rec_len=%zd, name_len=%d", dir->i_ino, error, (folio->index << PAGE_SHIFT) + offs, (unsigned long)le64_to_cpu(p->inode), rec_len, p->name_len); + } goto fail; Eend: p = (struct nilfs_dir_entry *)(kaddr + offs); - nilfs_error(sb, - "entry in directory #%lu spans the page boundary offset=%lu, inode=%lu", - dir->i_ino, (folio->index << PAGE_SHIFT) + offs, - (unsigned long)le64_to_cpu(p->inode)); + if (__ratelimit(&rs)) { + nilfs_error(sb, + "entry in directory #%lu spans the page boundary offset=%lu, inode=%lu", + dir->i_ino, (folio->index << PAGE_SHIFT) + offs, + (unsigned long)le64_to_cpu(p->inode)); + } fail: return false; } -- 2.43.0
