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pgcache read: protect against reads past end of the vm object size

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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@omnilan.de>
Tested by:	cy
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2021-02-15 05:34:06 +02:00
parent 184c1b9439
commit c61fae1475
1 changed files with 4 additions and 0 deletions
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4
sys/kern/vfs_vnops.c
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@ -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;