From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 170C94C10E8; Thu, 17 Sep 2026 15:37:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789659473; cv=none; b=kdQjv5ojf0KnAu+rsGmg3w7vIltqoun34e/zVCUjcYwMVgYKjwwDvczqLDODlG7ShrPbYU2IK9m76R5AH4OoM7UhbmLfS5FYOyphttturH6VE7pXpPPseGvyb2t6BmvN76rlAD2TZgiTZyGVLU91dytHVJD9Of0mVAYE4ppNrDQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789659473; c=relaxed/simple; bh=Ol0EeEBjoky0sgOFnc6H8wY1DuOglo19D17VZIGrdUA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=oMUOTD0Toew1TZItpi4axAe0b4+wDltBhOy6+E0+KAydYVweleWJ8toNzAw0gDy4a8XnwW3h5qEQuFEedt56taMrXDiMcRW0KWYId8Bqv6hktFzdUq9xGw3wfIA65r5YfIYQPyZg4ndy25Obh4ykU2+B/JXgktQLMn7DvxJNiEk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=a1zfbVOW; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="a1zfbVOW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 12F3D1F00893; Thu, 17 Sep 2026 15:37:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789659469; bh=ZBFnvprEvl08k80HabP06TprFvtBDAis0GkoV14c/h8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=a1zfbVOWsAsdBOVD3e/jccSeJ0AeOsMd+c6tI8579lUq1Pcly+yoZam98eofhioFU ugw51+M9bX8cYOoSe9z36Xe5TfNyKF/yqasVk/DydEMIrJikWUgkXwqK1gWk/XdoJy /HDw74GjvTinUT85Waexi+xxx7kIOVaiLBVnQcvQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Nicholas Carlini , Kumar Kartikeya Dwivedi , Alexei Starovoitov , Sasha Levin Subject: [PATCH 7.2 267/733] bpf: Preserve inner map identity in callback frames Date: Thu, 17 Sep 2026 16:09:35 +0100 Message-ID: <20260917151357.990762469@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260917151350.597953846@linuxfoundation.org> References: <20260917151350.597953846@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kumar Kartikeya Dwivedi [ Upstream commit b90c5d770dad910fb89e6c1b15052a8a1e8db752 ] Callback frame constructors initialize map-typed argument registers with __mark_reg_known_zero() and then restore map_ptr. This clears map_uid, which is the only field distinguishing inner maps that share an inner_map_meta template. When a timer callback invokes bpf_for_each_map_elem() on a second inner map, both the saved first map and the second map value can reach the nested callback as the same template with map_uid zero. bpf_timer_init() then accepts pairing the timer from the second map with the first map. The runtime records the first map in the timer without taking a reference. Freeing that map does not find the timer stored in the second map, so a later timer callback dereferences the freed map. Copy map_uid from the same caller register as map_ptr when constructing for-each, timer/workqueue, and task-work callback arguments. The existing identity check can then reject mismatched inner maps while allowing a callback value to be paired with its actual map. Fixes: 3e8ce29850f1 ("bpf: Prevent pointer mismatch in bpf_timer_init.") Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper") Fixes: 5c8fd7e2b5b0 ("bpf: bpf task work plumbing") Reported-by: Nicholas Carlini Suggested-by: Nicholas Carlini Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904104203.345917-8-memxor@gmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- kernel/bpf/verifier.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 14bd6889f6de9..be282185d5653 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9529,10 +9529,12 @@ int map_set_for_each_callback_args(struct bpf_verifier_env *env, callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY; __mark_reg_known_zero(&callee->regs[BPF_REG_2]); callee->regs[BPF_REG_2].map_ptr = caller->regs[BPF_REG_1].map_ptr; + callee->regs[BPF_REG_2].map_uid = caller->regs[BPF_REG_1].map_uid; callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE; __mark_reg_known_zero(&callee->regs[BPF_REG_3]); callee->regs[BPF_REG_3].map_ptr = caller->regs[BPF_REG_1].map_ptr; + callee->regs[BPF_REG_3].map_uid = caller->regs[BPF_REG_1].map_uid; /* pointer to stack or null */ callee->regs[BPF_REG_4] = caller->regs[BPF_REG_3]; @@ -9610,6 +9612,7 @@ static int set_timer_callback_state(struct bpf_verifier_env *env, int insn_idx) { struct bpf_map *map_ptr = caller->regs[BPF_REG_1].map_ptr; + u32 map_uid = caller->regs[BPF_REG_1].map_uid; /* bpf_timer_set_callback(struct bpf_timer *timer, void *callback_fn); * callback_fn(struct bpf_map *map, void *key, void *value); @@ -9617,14 +9620,17 @@ static int set_timer_callback_state(struct bpf_verifier_env *env, callee->regs[BPF_REG_1].type = CONST_PTR_TO_MAP; __mark_reg_known_zero(&callee->regs[BPF_REG_1]); callee->regs[BPF_REG_1].map_ptr = map_ptr; + callee->regs[BPF_REG_1].map_uid = map_uid; callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY; __mark_reg_known_zero(&callee->regs[BPF_REG_2]); callee->regs[BPF_REG_2].map_ptr = map_ptr; + callee->regs[BPF_REG_2].map_uid = map_uid; callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE; __mark_reg_known_zero(&callee->regs[BPF_REG_3]); callee->regs[BPF_REG_3].map_ptr = map_ptr; + callee->regs[BPF_REG_3].map_uid = map_uid; /* unused */ bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]); @@ -9724,6 +9730,7 @@ static int set_task_work_schedule_callback_state(struct bpf_verifier_env *env, int insn_idx) { struct bpf_map *map_ptr = caller->regs[BPF_REG_3].map_ptr; + u32 map_uid = caller->regs[BPF_REG_3].map_uid; /* * callback_fn(struct bpf_map *map, void *key, void *value); @@ -9731,14 +9738,17 @@ static int set_task_work_schedule_callback_state(struct bpf_verifier_env *env, callee->regs[BPF_REG_1].type = CONST_PTR_TO_MAP; __mark_reg_known_zero(&callee->regs[BPF_REG_1]); callee->regs[BPF_REG_1].map_ptr = map_ptr; + callee->regs[BPF_REG_1].map_uid = map_uid; callee->regs[BPF_REG_2].type = PTR_TO_MAP_KEY; __mark_reg_known_zero(&callee->regs[BPF_REG_2]); callee->regs[BPF_REG_2].map_ptr = map_ptr; + callee->regs[BPF_REG_2].map_uid = map_uid; callee->regs[BPF_REG_3].type = PTR_TO_MAP_VALUE; __mark_reg_known_zero(&callee->regs[BPF_REG_3]); callee->regs[BPF_REG_3].map_ptr = map_ptr; + callee->regs[BPF_REG_3].map_uid = map_uid; /* unused */ bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]); -- 2.53.0