xfs: Fix error pointer dereference

The function try_lookup_noperm() can return an error pointer and is not
checked for one.

Add checks for error pointer in xrep_adoption_check_dcache() and
xrep_adoption_zap_dcache().

Detected by Smatch:
fs/xfs/scrub/orphanage.c:449 xrep_adoption_check_dcache() error:
'd_child' dereferencing possible ERR_PTR()

fs/xfs/scrub/orphanage.c:485 xrep_adoption_zap_dcache() error:
'd_child' dereferencing possible ERR_PTR()

Fixes: 73597e3e42b4 ("xfs: ensure dentry consistency when the orphanage adopts a file")
Cc: stable@vger.kernel.org # v6.16
Signed-off-by: Ethan Tidmore <ethantidmore06@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Nirjhar Roy (IBM) <nirjhar.roy.lists@gmail.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

diff --git a/fs/xfs/scrub/orphanage.c b/fs/xfs/scrub/orphanage.c
index 52a108f6d5f40ff7902f9f14f834f3ead155b3f5..33c6db6b4498a7a7813e377cbe5fb71c0b3c5e4b 100644 (file)
--- a/fs/xfs/scrub/orphanage.c
+++ b/fs/xfs/scrub/orphanage.c
@@ -442,6 +442,11 @@ xrep_adoption_check_dcache(
                return 0;
 
        d_child = try_lookup_noperm(&qname, d_orphanage);
+       if (IS_ERR(d_child)) {
+               dput(d_orphanage);
+               return PTR_ERR(d_child);
+       }
+
        if (d_child) {
                trace_xrep_adoption_check_child(sc->mp, d_child);
 
@@ -479,7 +484,7 @@ xrep_adoption_zap_dcache(
                return;
 
        d_child = try_lookup_noperm(&qname, d_orphanage);
-       while (d_child != NULL) {
+       while (!IS_ERR_OR_NULL(d_child)) {
                trace_xrep_adoption_invalidate_child(sc->mp, d_child);
 
                ASSERT(d_is_negative(d_child));