git: c61fae1475f1 - main - pgcache read: protect against reads past end of the vm object size

[Konstantin Belousov]

The branch main has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=c61fae1475f1864dc4bba667b642f279afd44855

commit c61fae1475f1864dc4bba667b642f279afd44855
Author:     Konstantin Belousov <kib at FreeBSD.org>
AuthorDate: 2021-02-15 03:34:06 +0000
Commit:     Konstantin Belousov <kib at FreeBSD.org>
CommitDate: 2021-02-16 05:09:37 +0000

    pgcache read: protect against reads past end of the vm object size
    
    If uio_offset is past end of the object size, calculated resid is negative.
    Delegate handling this case to the locked read, as any other non-trivial
    situation.
    
    PR:     253158
    Reported by:    Harald Schmalzbauer <bugzilla.freebsd at omnilan.de>
    Tested by:      cy
    Sponsored by:   The FreeBSD Foundation
    MFC after:      1 week
---
 sys/kern/vfs_vnops.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
index f8943b3c07e7..71dd379558cb 100644
--- a/sys/kern/vfs_vnops.c
+++ b/sys/kern/vfs_vnops.c
@@ -950,6 +950,10 @@ vn_read_from_obj(struct vnode *vp, struct uio *uio)
 #else
 	vsz = atomic_load_64(&obj->un_pager.vnp.vnp_size);
 #endif
+	if (uio->uio_offset >= vsz) {
+		error = EJUSTRETURN;
+		goto out;
+	}
 	if (uio->uio_offset + resid > vsz)
 		resid = vsz - uio->uio_offset;