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[169.232.97.87]) by smtp.googlemail.com with ESMTPSA id 41be03b00d2f7-7ee452ae3a0sm6054991a12.37.2024.11.03.19.51.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 03 Nov 2024 19:51:43 -0800 (PST) From: Daniel Yang To: Jens Axboe , Pavel Begunkov , io-uring@vger.kernel.org (open list:IO_URING), linux-kernel@vger.kernel.org (open list) Cc: Daniel Yang , syzbot+05c0f12a4d43d656817e@syzkaller.appspotmail.com Subject: [PATCH] io_uring/rsrc: fix null ptr dereference in io_sqe_buffer_register Date: Sun, 3 Nov 2024 19:51:05 -0800 Message-Id: <20241104035105.192960-1-danielyangkang@gmail.com> X-Mailer: git-send-email 2.39.2 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The call stack io_sqe_buffer_register -> io_buffer_account_pin -> headpage_already_acct results in a null ptr dereference in the for loop. There is no guarantee that ctx->buf_table.nodes[i] is an allocated node so add a check if null before dereferencing. Signed-off-by: Daniel Yang Reported-by: syzbot+05c0f12a4d43d656817e@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D05c0f12a4d43d656817e Fixes: 661768085e99 ("io_uring/rsrc: get rid of the empty node and dummy_ub= uf") --- io_uring/rsrc.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c index af60d9f59..e2edb752a 100644 --- a/io_uring/rsrc.c +++ b/io_uring/rsrc.c @@ -581,6 +581,8 @@ static bool headpage_already_acct(struct io_ring_ctx *c= tx, struct page **pages, /* check previously registered pages */ for (i =3D 0; i < ctx->buf_table.nr; i++) { struct io_rsrc_node *node =3D ctx->buf_table.nodes[i]; + if (!node) + continue; struct io_mapped_ubuf *imu =3D node->buf; =20 for (j =3D 0; j < imu->nr_bvecs; j++) { --=20 2.39.2