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[47.55.120.4]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8b2357dbc51sm427542085a.29.2025.11.07.07.37.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Nov 2025 07:37:34 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1vHOWr-00000007nqz-3GJt; Fri, 07 Nov 2025 11:37:33 -0400 Date: Fri, 7 Nov 2025 11:37:33 -0400 From: Jason Gunthorpe To: Kriish Sharma Cc: Leon Romanovsky , Vlad Dumitrescu , Parav Pandit , Edward Srouji , linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+938fcd548c303fe33c1a@syzkaller.appspotmail.com Subject: Re: [PATCH] RDMA/core: Fix uninitialized gid in ib_nl_process_good_ip_rsep() Message-ID: <20251107153733.GA1859178@ziepe.ca> References: <20251107041002.2091584-1-kriish.sharma2006@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251107041002.2091584-1-kriish.sharma2006@gmail.com> On Fri, Nov 07, 2025 at 04:10:02AM +0000, Kriish Sharma wrote: > KMSAN reported a use of uninitialized memory in hex_byte_pack() > via ip6_string() when printing %pI6 from ib_nl_handle_ip_res_resp(). > If the LS_NLA_TYPE_DGID attribute is missing, 'gid' remains > uninitialized before being used in pr_info(), leading to a > KMSAN uninit-value report. > > Reported-by: syzbot+938fcd548c303fe33c1a@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=938fcd548c303fe33c1a > Fixes: ae43f8286730 ("IB/core: Add IP to GID netlink offload") > Signed-off-by: Kriish Sharma > --- > drivers/infiniband/core/addr.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/infiniband/core/addr.c b/drivers/infiniband/core/addr.c > index 61596cda2b65..4c602fcae12f 100644 > --- a/drivers/infiniband/core/addr.c > +++ b/drivers/infiniband/core/addr.c > @@ -99,7 +99,7 @@ static inline bool ib_nl_is_good_ip_resp(const struct nlmsghdr *nlh) > static void ib_nl_process_good_ip_rsep(const struct nlmsghdr *nlh) > { > const struct nlattr *head, *curr; > - union ib_gid gid; > + union ib_gid gid = {}; > struct addr_req *req; > int len, rem; > int found = 0; This doesn't seem right. We have this as the only caller: if (ib_nl_is_good_ip_resp(nlh)) ib_nl_process_good_ip_rsep(nlh); And ib_nl_is_good_ip_resp() does: ret = nla_parse_deprecated(tb, LS_NLA_TYPE_MAX - 1, nlmsg_data(nlh), nlmsg_len(nlh), ib_nl_addr_policy, NULL); static const struct nla_policy ib_nl_addr_policy[LS_NLA_TYPE_MAX] = { [LS_NLA_TYPE_DGID] = {.type = NLA_BINARY, .len = sizeof(struct rdma_nla_ls_gid), .validation_type = NLA_VALIDATE_MIN, .min = sizeof(struct rdma_nla_ls_gid)}, }; So I expect the nla_parse_deprecated() to fail if this: nla_for_each_attr(curr, head, len, rem) { if (curr->nla_type == LS_NLA_TYPE_DGID) memcpy(&gid, nla_data(curr), nla_len(curr)); } Doesn't find a DGID. So how can gid be uninitialized? The fix to whatever this is should be in ib_nl_is_good_ip_resp(). Jason