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Thu, 19 Feb 2026 03:27:01 -0800 (PST) Message-ID: <61386abf00c817e65ab70c994ed584fde339f9ed.camel@gmail.com> Subject: Re: [PATCH] xfs: Fix error pointer dereference From: "Nirjhar Roy (IBM)" To: Ethan Tidmore , Carlos Maiolino , NeilBrown Cc: Christian Brauner , linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org Date: Thu, 19 Feb 2026 16:56:56 +0530 In-Reply-To: <20260218195115.14049-1-ethantidmore06@gmail.com> References: <20260218195115.14049-1-ethantidmore06@gmail.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-27.el8_10) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: 7bit On Wed, 2026-02-18 at 13:51 -0600, Ethan Tidmore wrote: > The function try_lookup_noperm() can return an error pointer and is not > checked for one. Add checks for error pointer. Nit:In the subject, maybe just add the function name where the error pointer dereference is being fixed? > > 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: 06c567403ae5a ("Use try_lookup_noperm() instead of d_hash_and_lookup() outside of VFS") > Signed-off-by: Ethan Tidmore > --- > fs/xfs/scrub/orphanage.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/fs/xfs/scrub/orphanage.c b/fs/xfs/scrub/orphanage.c > index 52a108f6d5f4..cdb0f486f50c 100644 > --- a/fs/xfs/scrub/orphanage.c > +++ b/fs/xfs/scrub/orphanage.c > @@ -442,7 +442,7 @@ xrep_adoption_check_dcache( > return 0; > > d_child = try_lookup_noperm(&qname, d_orphanage); > - if (d_child) { > + if (!IS_ERR_OR_NULL(d_child)) { > trace_xrep_adoption_check_child(sc->mp, d_child); > > if (d_is_positive(d_child)) { > @@ -479,7 +479,7 @@ 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); Based on my limited knowledge of this change looks okay to me. I looked into the return values of try_lookup_noperm() and it does return error pointer which is not NULL. I also checked the other call sites of try_lookup_noperm() but I do see a mixed handling i.e, some places just checks for !ptr and some for IS_ERR_OR_NULL. For example in fs/autofs it checks with IS_ERR_OR_NULL whereas in fs/proc/base.c it just checks for !child. However, IMO, it is better to check for both NULL and error pointer if there is a possibility for both. --NR > > ASSERT(d_is_negative(d_child));