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Fri, 24 Jul 2026 14:46:58 -0700 (PDT) From: Fredric Cover To: sfrench@samba.org Cc: pc@manguebit.org, ronniesahlberg@gmail.com, sprasad@microsoft.com, tom@talpey.com, bharathsm@microsoft.com, linux-cifs@vger.kernel.org, linux-kernel@vger.kernel.org, Fredric Cover , stable@vger.kernel.org Subject: [PATCH v2 1/2] smb: client: harden DFS cache against invalid target hints Date: Fri, 24 Jul 2026 14:44:34 -0700 Message-ID: <20260724214435.1850384-2-fredric.cover.lkernel@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260724214435.1850384-1-fredric.cover.lkernel@gmail.com> References: <20260724023539.1596955-1-fredric.cover.lkernel@gmail.com> <20260724214435.1850384-1-fredric.cover.lkernel@gmail.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Currently, get_tgt_name() returns ERR_PTR(-ENOENT) when ce->tgthint is NULL, and dfs_cache_noreq_update_tgthint() assumes ce->tgthint is always valid. In preparation for clearing ce->tgthint in free_tgts(), harden callers of get_tgt_name() against ERR_PTR results and harden dfs_cache_noreq_update_tgthint() against NULL pointer dereferences. Cc: stable@vger.kernel.org Signed-off-by: Fredric Cover --- fs/smb/client/dfs_cache.c | 31 ++++++++++++++++++++++++------- 1 file changed, 24 insertions(+), 7 deletions(-) diff --git a/fs/smb/client/dfs_cache.c b/fs/smb/client/dfs_cache.c index 8cd93cd2f00f..c9ace4326a35 100644 --- a/fs/smb/client/dfs_cache.c +++ b/fs/smb/client/dfs_cache.c @@ -869,13 +869,22 @@ int dfs_cache_find(const unsigned int xid, struct cifs_ses *ses, const struct nl goto out_free_path; } - if (ref) - rc = setup_referral(path, ce, ref, get_tgt_name(ce)); - else + if (ref) { + char *target = get_tgt_name(ce); + + if (IS_ERR(target)) { + rc = PTR_ERR(target); + goto out_unlock; + } + rc = setup_referral(path, ce, ref, target); + } else { rc = 0; + } + if (!rc && tgt_list) rc = get_targets(ce, tgt_list); +out_unlock: up_read(&htable_rw_lock); out_free_path: @@ -915,10 +924,17 @@ int dfs_cache_noreq_find(const char *path, struct dfs_info3_param *ref, goto out_unlock; } - if (ref) - rc = setup_referral(path, ce, ref, get_tgt_name(ce)); - else + if (ref) { + char *target = get_tgt_name(ce); + + if (IS_ERR(target)) { + rc = PTR_ERR(target); + goto out_unlock; + } + rc = setup_referral(path, ce, ref, target); + } else { rc = 0; + } if (!rc && tgt_list) rc = get_targets(ce, tgt_list); @@ -959,7 +975,8 @@ void dfs_cache_noreq_update_tgthint(const char *path, const struct dfs_cache_tgt t = READ_ONCE(ce->tgthint); - if (unlikely(!strcasecmp(it->it_name, t->name))) + /* Check 't' in case ce->tgthint was cleared by free_tgts() */ + if (t && unlikely(!strcasecmp(it->it_name, t->name))) goto out_unlock; list_for_each_entry(t, &ce->tlist, list) { -- 2.53.0