From 883b776abe48fed8ef615f4ff7e91113a6c4dffb Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Tue, 22 Sep 2026 12:41:02 +0200 Subject: [PATCH] isofs: Fix handling of directories with tight blocks Thomas has reported that after commit b2eb2e288604 ("isofs: Drop support of directory entries straddling blocks") some isofs images of Fedora miss some entries in some directories. The problem is triggered when directory entries are packed in a block in such a way that they exactly fit the block (which BTW mkisofs doesn't do so I didn't catch this bug when testing with my images). Fix readdir and lookup code to properly transition to the next block when directory block is tightly packed. Link: https://bugzilla.redhat.com/show_bug.cgi?id=2535353 Reported-by: Thomas Schmitt Reported-by: Matthias Goergens Fixes: b2eb2e288604 ("isofs: Drop support of directory entries straddling blocks") Reviewed-by: Thomas Schmitt Signed-off-by: Jan Kara --- fs/isofs/dir.c | 20 ++++++++------------ fs/isofs/namei.c | 16 +++++++++------- 2 files changed, 17 insertions(+), 19 deletions(-) diff --git a/fs/isofs/dir.c b/fs/isofs/dir.c index c7ca7603e97a..28741251d56e 100644 --- a/fs/isofs/dir.c +++ b/fs/isofs/dir.c @@ -110,25 +110,21 @@ static int do_isofs_readdir(struct inode *inode, struct file *file, return 0; } - de = (struct iso_directory_record *) (bh->b_data + offset); - - de_len = *(unsigned char *)de; - + de = (struct iso_directory_record *)(bh->b_data + offset); /* - * If the length byte is zero, we should move on to the next - * CDROM sector. If we are at the end of the directory, we - * kick out of the while loop. + * If we are at the end of a block (or at its zero-padded + * tail), move on to the next CDROM sector. If we are at the + * end of the directory, we'll abort the while loop. */ - - if (de_len == 0) { + if (offset >= bufsize || de->length[0] == 0) { brelse(bh); bh = NULL; - ctx->pos = (ctx->pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1); - block = ctx->pos >> bufbits; + block++; + ctx->pos = (loff_t)block << bufbits; offset = 0; continue; } - + de_len = de->length[0]; block_saved = block; offset_saved = offset; offset += de_len; diff --git a/fs/isofs/namei.c b/fs/isofs/namei.c index 010682f5901a..4fba1bf7f016 100644 --- a/fs/isofs/namei.c +++ b/fs/isofs/namei.c @@ -74,18 +74,20 @@ isofs_find_entry(struct inode *dir, struct dentry *dentry, return 0; } - de = (struct iso_directory_record *) (bh->b_data + offset); - - de_len = *(unsigned char *) de; - if (!de_len) { + de = (struct iso_directory_record *)(bh->b_data + offset); + /* + * If we are at the end of the block or at its zero-padded + * tail, move to the next block. + */ + if (offset >= bufsize || de->length[0] == 0) { brelse(bh); bh = NULL; - f_pos = (f_pos + ISOFS_BLOCK_SIZE) & ~(ISOFS_BLOCK_SIZE - 1); - block = f_pos >> bufbits; + block++; + f_pos = block << bufbits; offset = 0; continue; } - + de_len = de->length[0]; block_saved = bh->b_blocknr; offset_saved = offset; offset += de_len;