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 66F58343893; Sat, 12 Sep 2026 09:44:33 +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=1789206274; cv=none; b=BdSnCdfoy1e8RN+mlmtgI/79TVTHWZABgZssdhdXv45E9/U8NYFlVs62+qCN+WJw0NfsIsOTZV3rRgVfFXh9Pye8u5aJilQoo63QhxSZCKbiraVQlI5TV6fP9M0bMWE8ZKgIR2Xntn7aC1Y0rjxbzTVvTuBJbCJBLJEol1I9NtI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789206274; c=relaxed/simple; bh=76BnmaT4An9fpZzngA60P6zvc3lHTo4fUrZzXwIACJI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ah4G93qRbWvtLcz48ozYkF1VDPwaGQEBxgE4xiJoH/cEpDDoOHwmk/7g7yyceD2/Hp1+Gtzkh/eYJhK+8Htt0wFAZkS9Y1PTMAHBpYnMTG0EUp9+J+owDhg9mM1ZBr1S4hNPBS9z3QxcEN9rmFRWr/GcGIpYnPz5nXj2dhwm3RM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=B1hyH5uv; 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="B1hyH5uv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 048DA1F000FF; Sat, 12 Sep 2026 09:44:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789206273; bh=etc8suvqqdxAzj2Pht+jJWoSoeilx05TAZgKdcLJ6LQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=B1hyH5uvMUkV6cyIz4ViMFg1sCGAYxfTaVatCqhVXF7G2OlT/RR9I5WTwPAim9jlW FWoN/YGMpSsQ3DtYw4aEno9Etm2srLyfsUndc3KdhHHSOCJl2cIT4ozOt8LBonvM2Q PM2iqqMp3vCcbVmNj1wpj/6WuCRi36pPIfh7b7Zg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Leon Hwang , Andrii Nakryiko , Sasha Levin Subject: [PATCH 6.18 0172/1518] bpf: Copy per-CPU map value padding in copy_map_value_long() Date: Sat, 12 Sep 2026 08:39:01 +0200 Message-ID: <20260912065627.387420824@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065623.398859879@linuxfoundation.org> References: <20260912065623.398859879@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Leon Hwang [ Upstream commit 7cf9cd98cf6f0df3befc167ca6b54c07014d71de ] In kernel, per-CPU map elements are stored with round_up(map->value_size, 8) bytes. On UAPI lookup paths, it copies the rounded size for each CPU into a temporary buffer. However, copy_map_value_long() passes 'map->value_size' to bpf_obj_memcpy(). When the map has special fields, bpf_obj_memcpy() copies around those fields with memcpy(), and does not copy the tail padding between 'map->value_size' and round_up(map->value_size, 8). The temporary UAPI lookup buffers are allocated without __GFP_ZERO. As a result, when the per-CPU map's value size is not equal to round_up(map->value_size, 8), UAPI LOOKUP_ELEM and its variants can return stale heap contents from that padding to user space. The same issue applies to bpf_iter for per-CPU maps. Pass round_up(map->value_size, 8) to bpf_obj_memcpy() from copy_map_value_long(), so per-CPU maps both with and without special fields copy the entire per-CPU slot. Remove the now redundant round_up() from bpf_obj_memcpy()'s long_memcpy path. Fixes: 448325199f57 ("bpf: Add copy_map_value_long to copy to remote percpu memory") Signed-off-by: Leon Hwang Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20260624155115.85196-2-leon.hwang@linux.dev Signed-off-by: Sasha Levin --- include/linux/bpf.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index e264c695f31ce..84a8afc6e6df3 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -536,7 +536,7 @@ static inline void bpf_obj_memcpy(struct btf_record *rec, if (IS_ERR_OR_NULL(rec)) { if (long_memcpy) - bpf_long_memcpy(dst, src, round_up(size, 8)); + bpf_long_memcpy(dst, src, size); else memcpy(dst, src, size); return; @@ -559,7 +559,7 @@ static inline void copy_map_value(struct bpf_map *map, void *dst, void *src) static inline void copy_map_value_long(struct bpf_map *map, void *dst, void *src) { - bpf_obj_memcpy(map->record, dst, src, map->value_size, true); + bpf_obj_memcpy(map->record, dst, src, round_up(map->value_size, 8), true); } static inline void bpf_obj_swap_uptrs(const struct btf_record *rec, void *dst, void *src) -- 2.53.0