From nobody Sat Jul 25 00:52:35 2026 Received: from mail-pf1-f170.google.com (mail-pf1-f170.google.com [209.85.210.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 67DAE478874 for ; Tue, 21 Jul 2026 09:57:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.170 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784627839; cv=none; b=pARz7areCOyMnwwMPVjcj8fK/P2ozPPAIyImZKhpkqLhBNBs2cfE6ZVx39x2ioVoGDomrbyhXcA05Hpsz4jZELfYHY1DR3MZt1fSBOimPgci69mYFuo2z46QSE+B73MGaokqiM90O5+P30uiGsDQ8axOOo/UWQ+8xSNvN6XdPjs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784627839; c=relaxed/simple; bh=pR5vKx+ifxyexrw8+sqWJetVzv0/JsCsCmISYtkw/Zc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ButIo2aSB/qhPCKU4kWkqBXvvOZTEUM828kGMNdNzNZ1GaffQAfT8VFEhK5UQkevMG9LEx2W7AVn4IZkhkTIVYfGx4Xx4930ooKf3NEfjpQ4dzmwcZ12F99kgBJIgJmrbZgWt9vlFBCHf+rIpcICVtgJMraF/AxduGAE+9Jg4us= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=IyQ8CSJZ; arc=none smtp.client-ip=209.85.210.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="IyQ8CSJZ" Received: by mail-pf1-f170.google.com with SMTP id d2e1a72fcca58-848d21bbaffso11105322b3a.0 for ; Tue, 21 Jul 2026 02:57:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1784627837; x=1785232637; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=Vi8Y5Mae0eMxJXexF7C1mNZVoJhUCTDqrvtov6btneE=; b=IyQ8CSJZeA35GEUxdtBIupbv0zSyEg3bChBc/R6eoJeq9823/yzJBl3i4WL/as8T3L a2T67BOhg0vxam+igL1pgiJLJK0D6ENOh0AGewqeSKodjyOrWZQyrWlNA4qGyMnl6rPx 9LGBVRl4OyUVGCpTyQH9zQFS+g5GTpLaXX/5cGbLH/T1Y0kzzhcyKzdK00OGTCjJIg7E 2TLGiCPiVCuJUyDjKXmzH7fcaOik8f0in4CrskVzq5h4ahXuJrxHw2Axo/3a/yWbu7Hc CFhgon756vDaTXvcGZ7ns/Fvzsx/2mx8Trq3SdvLDV3djunYRLGDKUvowwpqzeJehR+x /xbQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1784627837; x=1785232637; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=Vi8Y5Mae0eMxJXexF7C1mNZVoJhUCTDqrvtov6btneE=; b=qTPq3t7Tkecw5CAlJb1iiQQUbqzIgfeDZAXNL2Aj6Us8nhWLa+wDrho3ra5hFxEZqx Z4FfG9uUO7lw/Vzhf6ahnRB84vDjuqWR++9DCH7C1eWpJrg+K1HBfq4u4uCA0tSUvjbG j37k6HwUEUIWs/FmIVZW6+UHNTNJLwCYzmVKqd/NNpboSMKAksckCdPwSDfwTtrat/Tl BdGEDWougIg0Y31RvJ0VhFodJTDElTUXSZ4OB6xdxUPksbwwL8LtxehWzVyln+o2cBuo dE7bXdl/sfK0xqI/gexlk64SPEGtsy2Axfuct0pOjs+KeqBq5NH187fAVDJhsBv/zubF 2dzw== X-Forwarded-Encrypted: i=1; AHgh+RqHKg9UogkFUGIsF52dnl4jv0tqSMcr2MbqSlzYKl9lTmHDw0qdBDSv7e7ihM0KEm1P8eVvm6Y5hXtPvyc=@vger.kernel.org X-Gm-Message-State: AOJu0YwAmMXWRsl6oMp5SMLfrrQsDRSBhl7mAHI7a0iRhqXwOmWEVt0d kuWsnufPcmzzinO9BQ18C6qQs7OCXKNNlbb21HfWnH728hZIwT3xXHhg X-Gm-Gg: AfdE7cmahr+3U2FRpvjTfzTa6PNXOR6WTRuX25dTNf6NSZqkGrcVpngt0gTJM/0WU/K 1XND56IeR9TOAvi1jm2jwq8lpHbeOyksK5bJ2I+hOrJ75wc5shW3BBalJrTL6pHf/3+e4v4d7eR n0JIC7CKYPMBEM+gz8Yw+1rRvF40LJKy3A/InTp8mOPwq74ra9FMJj9gVec4WY4R+fH8MqCtEgD 2aHBqe6H2UffRlu84sdVDcFlKdZSia0tRnERuJIcY/x+Jsi4+JMcgZj5wHvmnrwgZVJ9NsY0LDc YfHtYMwxUgzLXJYBBNBndlZK2Ik/OG3RibGbzLGCUouBP6JVCp+xYDrHCPOYg+vkeb+E8Omoetw EWn8RhRdLDj7tW2gsqj/qAVyEB8cFWm47GOeUuURzAbmWauTpeG9h2Fl+FB2DsOuGZQV27L2BLd 1PzHlF9gb5aH70skvYY4k8MC2jOU6Rs1EqyUR3 X-Received: by 2002:a05:6a21:ec42:10b0:3c4:de3:816c with SMTP id adf61e73a8af0-3c40de381f5mr2669733637.37.1784627837591; Tue, 21 Jul 2026 02:57:17 -0700 (PDT) Received: from localhost.localdomain ([125.20.165.194]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-3142a1bb770sm49460081eec.16.2026.07.21.02.57.14 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 21 Jul 2026 02:57:16 -0700 (PDT) From: Aayush7352 To: io-uring@vger.kernel.org Cc: Jens Axboe , linux-kernel@vger.kernel.org, Aayush Dixit Subject: [PATCH] io_uring/kbuf: fix UAF in buffer selection when access_ok fails on expanded iovec Date: Tue, 21 Jul 2026 15:27:11 +0530 Message-ID: <20260721095711.80711-1-aayushdixit924@gmail.com> X-Mailer: git-send-email 2.55.0 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" From: Aayush Dixit In io_ring_buffers_peek(), when the buffer ring is expanded (KBUF_MODE_EXPAND), arg->iovs is set to a newly kmalloced array. If access_ok() then fails on a buffer entry, the error path kfrees the new array but does not restore arg->iovs to the original value (org_iovs). arg->iovs is left dangling and will be reused on retry, causing a use-after-free when the caller retries the buffer selection. Fix by restoring arg->iovs =3D org_iovs after the kfree on the error path, so the caller's state remains coherent on retry. Fixes: b3e0216c97e3 ("io_uring: add buffer ring support") Cc: io-uring@vger.kernel.org Signed-off-by: Aayush7352 --- io_uring/kbuf.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c index de0129bce..eab4de8a7 100644 --- a/io_uring/kbuf.c +++ b/io_uring/kbuf.c @@ -314,8 +314,10 @@ static int io_ring_buffers_peek(struct io_kiocb *req, = struct buf_sel_arg *arg, iov->iov_base =3D u64_to_user_ptr(READ_ONCE(buf->addr)); iov->iov_len =3D len; if (unlikely(!access_ok(iov->iov_base, len))) { - if (arg->iovs !=3D org_iovs) + if (arg->iovs !=3D org_iovs) { kfree(arg->iovs); + arg->iovs =3D org_iovs; + } return -EFAULT; } iov++; --=20 2.55.0