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 8DEB122D7A9 for ; Thu, 16 Jul 2026 05:09:18 +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=1784178559; cv=none; b=QCcCkP9ZlFRlZYTlK+PzSyfd/y3DYg7prpPjIA2OIcpl5e33r6blhjM17kYUJKwhjldAnI2vHHTLS6gR6WJPlKNYqRMRDTXelQxlmAT7gJ94Mcz7Ni8Bv1CqIx0R2UrRZDLBCQubq9modkbO8LlOCeS3UMeNqC/QXaSfBivumTw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784178559; c=relaxed/simple; bh=VqbJhFo04IkLuj27mppzfA2BQ84FFqrWh2K2V37fTq0=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=EvQrXx8687p1NpVJAWiPNgV/I0FStOKQu1WMxLDhN+MJmCm36QjZVGtQfl2nYRDPnvZE0vChFa1LOP0RcW+AJfspYduAvD7N8pzaYYwVNHCX8BTLC2/Fd3h7fLfetLYL1AZsoRV7o262pC/ugdlYC7Heq1pj+jnSdTzP2rk1OAM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=iRWDkNNB; 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="iRWDkNNB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F3F6B1F000E9; Thu, 16 Jul 2026 05:09:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784178558; bh=iVuJSOJIDgPO4pmJA4KRQpnH7dxfZbI0Ax/r+OPL4us=; h=Subject:To:Cc:From:Date; b=iRWDkNNBcSXdeds4WXvACOGDxV55JuRsHoxV/7wzkRsjb6ZtUeiaLuPdABPINxcRn uvmvbccAzg53HOdF3MNCMweOmcNQU8uNdT5CqhmbOJJD3WDB+z1crD+G4ZcgVjElLk ZfFw+O/EGKglMXJZpCdDjE1WtDRROJWyp5aPhWto= Subject: FAILED: patch "[PATCH] bpf: Reject BPF_MAP_TYPE_INODE_STORAGE creation if BPF LSM is" failed to apply to 5.10-stable tree To: mattbobrowski@google.com,ameryhung@gmail.com,awo@kakao.com,daniel@iogearbox.net,emil@etsalapatis.com Cc: From: Date: Thu, 16 Jul 2026 07:09:01 +0200 Message-ID: <2026071601-concerned-arousal-ac66@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x a6f0643e4f63cfaa0d5d4a69de4f132eac4b8fe4 # git commit -s git send-email --to '' --in-reply-to '2026071601-concerned-arousal-ac66@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From a6f0643e4f63cfaa0d5d4a69de4f132eac4b8fe4 Mon Sep 17 00:00:00 2001 From: Matt Bobrowski Date: Sun, 28 Jun 2026 20:11:03 +0000 Subject: [PATCH] bpf: Reject BPF_MAP_TYPE_INODE_STORAGE creation if BPF LSM is uninitialized When CONFIG_BPF_LSM=y is set, BPF inode storage maps (BPF_MAP_TYPE_INODE_STORAGE) are compiled into the kernel. However, if the BPF LSM is not explicitly enabled at boot time (e.g. omitted from the "lsm=" boot parameter), lsm_prepare() is never executed for the BPF LSM. Consequently, the BPF inode security blob offset (bpf_lsm_blob_sizes.lbs_inode) is never initialized and remains at its default compiled size of 8 bytes instead of being updated to a valid offset past the reserved struct rcu_head (typically 16 bytes or more). When a privileged user creates and updates a BPF_MAP_TYPE_INODE_STORAGE map, bpf_inode() evaluates inode->i_security + 8. This erroneously aliases the struct rcu_head.func callback pointer at the beginning of the inode->i_security blob. During subsequent map element cleanup or inode destruction, writing NULL to owner_storage clears the queued RCU callback pointer. When rcu_do_batch() later executes the queued callback, it attempts an instruction fetch at address 0x0, triggering an immediate kernel panic. Fix this by introducing a global bpf_lsm_initialized boolean flag marked with __ro_after_init. Set this flag to true inside bpf_lsm_init() when the LSM framework successfully registers the BPF LSM. Gate map allocation in inode_storage_map_alloc() on this flag, returning -EOPNOTSUPP if the BPF LSM is in turn uninitialized. This fail-fast approach prevents userspace from allocating inode storage maps when the supporting BPF LSM infrastructure is absent, avoiding zombie map states. Fixes: 8ea636848aca ("bpf: Implement bpf_local_storage for inodes") Reported-by: oxsignal Signed-off-by: Matt Bobrowski Signed-off-by: Daniel Borkmann Reviewed-by: Emil Tsalapatis Reviewed-by: Amery Hung Link: https://lore.kernel.org/bpf/20260628201103.3624525-1-mattbobrowski@google.com diff --git a/include/linux/bpf_lsm.h b/include/linux/bpf_lsm.h index 143775a27a2a..dda272d78f01 100644 --- a/include/linux/bpf_lsm.h +++ b/include/linux/bpf_lsm.h @@ -14,6 +14,8 @@ #ifdef CONFIG_BPF_LSM +extern bool bpf_lsm_initialized __ro_after_init; + #define LSM_HOOK(RET, DEFAULT, NAME, ...) \ RET bpf_lsm_##NAME(__VA_ARGS__); #include @@ -56,6 +58,8 @@ bool bpf_lsm_hook_returns_errno(u32 btf_id); #else /* !CONFIG_BPF_LSM */ +#define bpf_lsm_initialized false + static inline bool bpf_lsm_is_sleepable_hook(u32 btf_id) { return false; diff --git a/kernel/bpf/bpf_inode_storage.c b/kernel/bpf/bpf_inode_storage.c index 0da8d923e39d..f9e81060c1f4 100644 --- a/kernel/bpf/bpf_inode_storage.c +++ b/kernel/bpf/bpf_inode_storage.c @@ -178,6 +178,15 @@ static int notsupp_get_next_key(struct bpf_map *map, void *key, static struct bpf_map *inode_storage_map_alloc(union bpf_attr *attr) { + /* + * Do not allow allocation of BPF_MAP_TYPE_INODE_STORAGE if the BPF LSM + * was not initialized by the LSM framework at boot. Without proper + * initialization, the BPF inode security blob offset remains unprepared, + * causing bpf_inode() to calculate an invalid memory offset and corrupt + * inode->i_security. + */ + if (!bpf_lsm_initialized) + return ERR_PTR(-EOPNOTSUPP); return bpf_local_storage_map_alloc(attr, &inode_cache); } diff --git a/security/bpf/hooks.c b/security/bpf/hooks.c index 40efde233f3a..7b98f5d1e2be 100644 --- a/security/bpf/hooks.c +++ b/security/bpf/hooks.c @@ -7,6 +7,8 @@ #include #include +bool bpf_lsm_initialized __ro_after_init; + static struct security_hook_list bpf_lsm_hooks[] __ro_after_init = { #define LSM_HOOK(RET, DEFAULT, NAME, ...) \ LSM_HOOK_INIT(NAME, bpf_lsm_##NAME), @@ -24,6 +26,7 @@ static int __init bpf_lsm_init(void) { security_add_hooks(bpf_lsm_hooks, ARRAY_SIZE(bpf_lsm_hooks), &bpf_lsmid); + bpf_lsm_initialized = true; pr_info("LSM support for eBPF active\n"); return 0; }