6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx> commit 985ebec4ab0a28bb5910c3b1481a40fbf7f9e61d upstream. 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@xxxxxxxxx Fixes: 2ba466d74ed7 ("nilfs2: directory entry operations") Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx> Reported-by: syzbot+96d5d14c47d97015c624@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=96d5d14c47d97015c624 Tested-by: syzbot+96d5d14c47d97015c624@xxxxxxxxxxxxxxxxxxxxxxxxx Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/nilfs2/dir.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/nilfs2/dir.c +++ b/fs/nilfs2/dir.c @@ -70,7 +70,7 @@ static inline unsigned int nilfs_chunk_s */ 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)
