From 12427de9439d68b8e96ba6f50b601ef15f437612 Mon Sep 17 00:00:00 2001 From: Phillip Lougher <phillip@squashfs.org.uk> Date: Mon, 13 Nov 2023 16:09:01 +0000 Subject: [PATCH] Squashfs: fix variable overflow triggered by sysbot Sysbot reports a slab out of bounds write in squashfs_readahead(). This is ultimately caused by a file reporting an (infeasibly) large file size (1407374883553280 bytes) with the minimum block size of 4K. This causes variable overflow. Link: https://lkml.kernel.org/r/20231113160901.6444-1-phillip@squashfs.org.uk Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk> Reported-by: syzbot+604424eb051c2f696163@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/000000000000b1fda20609ede0d1@google.com/ Signed-off-by: Andrew Morton <akpm@linux-foundation.org> --- fs/squashfs/file.c | 3 ++- fs/squashfs/file_direct.c | 6 +++--- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c index 8ba8c4c507707..e8df6430444b0 100644 --- a/fs/squashfs/file.c +++ b/fs/squashfs/file.c @@ -544,7 +544,8 @@ static void squashfs_readahead(struct readahead_control *ractl) struct squashfs_page_actor *actor; unsigned int nr_pages = 0; struct page **pages; - int i, file_end = i_size_read(inode) >> msblk->block_log; + int i; + loff_t file_end = i_size_read(inode) >> msblk->block_log; unsigned int max_pages = 1UL << shift; readahead_expand(ractl, start, (len | mask) + 1); diff --git a/fs/squashfs/file_direct.c b/fs/squashfs/file_direct.c index f1ccad519e28c..763a3f7a75f6d 100644 --- a/fs/squashfs/file_direct.c +++ b/fs/squashfs/file_direct.c @@ -26,10 +26,10 @@ int squashfs_readpage_block(struct page *target_page, u64 block, int bsize, struct inode *inode = target_page->mapping->host; struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info; - int file_end = (i_size_read(inode) - 1) >> PAGE_SHIFT; + loff_t file_end = (i_size_read(inode) - 1) >> PAGE_SHIFT; int mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1; - int start_index = target_page->index & ~mask; - int end_index = start_index | mask; + loff_t start_index = target_page->index & ~mask; + loff_t end_index = start_index | mask; int i, n, pages, bytes, res = -ENOMEM; struct page **page; struct squashfs_page_actor *actor; -- GitLab