lkml.org 
[lkml]   [2023]   [Nov]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] Squashfs: Fix variable overflow triggered by sysbot
Date
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.

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/
---
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 8ba8c4c50770..e8df6430444b 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 f1ccad519e28..763a3f7a75f6 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;
--
2.35.1
\
 
 \ /
  Last update: 2023-11-20 13:58    [W:8.445 / U:0.056 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site