nilfs2: avoid overflowing segment numbers in nilfs_ioctl_clean_segments()

nsegs is read from userspace.  Limit its value and avoid overflowing nsegs
* sizeof(__u64) in the subsequent call to memdup_user().

This patch complements 481fe17e973fb9 ("nilfs2: potential integer overflow
in nilfs_ioctl_clean_segments()").

Signed-off-by: Xi Wang <xi.wang@gmail.com>
Cc: Haogang Chen <haogangchen@gmail.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index 8866496..2a70fce 100644 (file)
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -603,6 +603,8 @@ static int nilfs_ioctl_clean_segments(struct inode *inode, struct file *filp,
        nsegs = argv[4].v_nmembs;
        if (argv[4].v_size != argsz[4])
                goto out;
+       if (nsegs > UINT_MAX / sizeof(__u64))
+               goto out;
 
        /*
         * argv[4] points to segment numbers this ioctl cleans.  We