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Squashfs: fix variable overflow triggered by sysbot

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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>
This commit is contained in:
Phillip Lougher 2023-11-13 16:09:01 +00:00 committed by Andrew Morton
parent 44e3876d26
commit 12427de943
2 changed files with 5 additions and 4 deletions
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3
fs/squashfs/file.c
View File

@ -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);

6
fs/squashfs/file_direct.c
View File

@ -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;