git: bec758f641df - releng/12.1 - msdosfs: Fix a leak of dirent padding bytes

[Ed Maste]

The branch releng/12.1 has been updated by emaste:

URL: https://cgit.FreeBSD.org/src/commit/?id=bec758f641df1de04aca2633bfda6b1bacb48415

commit bec758f641df1de04aca2633bfda6b1bacb48415
Author:     Mark Johnston <markj at FreeBSD.org>
AuthorDate: 2020-12-27 21:52:30 +0000
Commit:     Ed Maste <emaste at FreeBSD.org>
CommitDate: 2021-01-29 00:59:53 +0000

    msdosfs: Fix a leak of dirent padding bytes
    
    This was missed in r340856 / commit
    6d2e2df764199f0a15fd743e79599391959cc17d.  Three bytes from the kernel
    stack may be leaked when reading directory entries.
    
    Reported by:    Syed Faraz Abrar <faraz at elttam.com>
    
    (cherry picked from commit 599f90446376370eb365a0fde857ea2b5766873a)
    (cherry picked from commit 5ece34669c27a61f78cd0f6e0759c17f7787aebb)
    
    Approved by:    so
    Security:       CVE-2020-25579
---
 sys/fs/msdosfs/msdosfs_vnops.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sys/fs/msdosfs/msdosfs_vnops.c b/sys/fs/msdosfs/msdosfs_vnops.c
index 8bd944661420..b5a5409c2582 100644
--- a/sys/fs/msdosfs/msdosfs_vnops.c
+++ b/sys/fs/msdosfs/msdosfs_vnops.c
@@ -1687,6 +1687,7 @@ msdosfs_readdir(struct vop_readdir_args *ap)
 			dirbuf.d_reclen = GENERIC_DIRSIZ(&dirbuf);
 			/* NOTE: d_off is the offset of the *next* entry. */
 			dirbuf.d_off = offset + sizeof(struct direntry);
+			dirent_terminate(&dirbuf);
 			if (uio->uio_resid < dirbuf.d_reclen) {
 				brelse(bp);
 				goto out;