diff options
| author | Ryusuke Konishi <konishi.ryusuke@gmail.com> | 2024-11-20 02:23:37 +0900 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-12-05 19:54:43 -0800 |
| commit | 985ebec4ab0a28bb5910c3b1481a40fbf7f9e61d (patch) | |
| tree | 0318e0f5423610154a30417aead8ffc9abe8c31e /fs/nilfs2 | |
| parent | e30a0361b8515d424c73c67de1a43e45a13b8ba2 (diff) | |
nilfs2: fix potential out-of-bounds memory access in nilfs_find_entry()
Syzbot reported that when searching for records in a directory where the
inode's i_size is corrupted and has a large value, memory access outside
the folio/page range may occur, or a use-after-free bug may be detected if
KASAN is enabled.
This is because nilfs_last_byte(), which is called by nilfs_find_entry()
and others to calculate the number of valid bytes of directory data in a
page from i_size and the page index, loses the upper 32 bits of the 64-bit
size information due to an inappropriate type of local variable to which
the i_size value is assigned.
This caused a large byte offset value due to underflow in the end address
calculation in the calling nilfs_find_entry(), resulting in memory access
that exceeds the folio/page size.
Fix this issue by changing the type of the local variable causing the bit
loss from "unsigned int" to "u64". The return value of nilfs_last_byte()
is also of type "unsigned int", but it is truncated so as not to exceed
PAGE_SIZE and no bit loss occurs, so no change is required.
Link: https://lkml.kernel.org/r/20241119172403.9292-1-konishi.ryusuke@gmail.com
Fixes: 2ba466d74ed7 ("nilfs2: directory entry operations")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: syzbot+96d5d14c47d97015c624@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=96d5d14c47d97015c624
Tested-by: syzbot+96d5d14c47d97015c624@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'fs/nilfs2')
| -rw-r--r-- | fs/nilfs2/dir.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/nilfs2/dir.c b/fs/nilfs2/dir.c index 14e8d82f8629..0a3aea6c416b 100644 --- a/fs/nilfs2/dir.c +++ b/fs/nilfs2/dir.c @@ -70,7 +70,7 @@ static inline unsigned int nilfs_chunk_size(struct inode *inode) */ static unsigned int nilfs_last_byte(struct inode *inode, unsigned long page_nr) { - unsigned int last_byte = inode->i_size; + u64 last_byte = inode->i_size; last_byte -= page_nr << PAGE_SHIFT; if (last_byte > PAGE_SIZE) |