On Wed, May 13, 2020 at 8:46 PM Smalley <stephen.smalley.work@xxxxxxxxx> wrote: > > From: Stephen Smalley <stephen.smalley.work@xxxxxxxxx> > > Prior to rename(2)'ing new files into place, fsync(2) them to ensure > the contents will be fully written prior to rename. While we are here, > also fix checking of write(2) to detect short writes. This code could > be more generally improved but keeping to the minimal changes required > to fix this bug. > > Fixes: https://github.com/SELinuxProject/selinux/issues/237 > Signed-off-by: Stephen Smalley <stephen.smalley.work@xxxxxxxxx> > --- > libsemanage/src/semanage_store.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c > index 859c0a22..3cac36d4 100644 > --- a/libsemanage/src/semanage_store.c > +++ b/libsemanage/src/semanage_store.c > @@ -735,7 +735,7 @@ int semanage_copy_file(const char *src, const char *dst, mode_t mode) > } > umask(mask); > while (retval == 0 && (amount_read = read(in, buf, sizeof(buf))) > 0) { > - if (write(out, buf, amount_read) < 0) { > + if (write(out, buf, amount_read) != amount_read) { > errsv = errno; > retval = -1; > } If I remember correctly, errno is not defined if a short write happens. If this is confirmed and if you want to keep the patch short, you could for example use errsv = EIO if write() returned a value different from -1 and from amount_read. Thanks, Nicolas > @@ -745,6 +745,10 @@ int semanage_copy_file(const char *src, const char *dst, mode_t mode) > retval = -1; > } > close(in); > + if (fsync(out) < 0) { > + errsv = errno; > + retval = -1; > + } > if (close(out) < 0) { > errsv = errno; > retval = -1; > -- > 2.23.3 >
