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 1A0863DC4C8 for ; Mon, 27 Jul 2026 21:00:15 +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=1785186016; cv=none; b=C3BG8rAlZ0/WKOYn9q2d4qXsZj+s1ZIv8H64ugF+DTRko91f+A2smqGcvW9uMd+xTLZUCOodNua8dbLKAO41VUEj2Sk4MCQxupyZu9HLsX5Zml7GjwUhZO6K9cLjLanpcBg4QQQmPblA5Yr0BsoHgriNr3Vti5g3urowT5vBfVc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785186016; c=relaxed/simple; bh=acFxkXi6iovvKFSWGLs4eelSV6ygbb84JY0hBtFLYo8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nqoD2eNgVrR17q3TvCqBq/q0rvbcJcZ1LJj/yzazPtMGoMoB40uKEOvDIZPNv+uHCVRTAY9Tao3Jk7SlOJ729Ty3+5kSC/ODOFSO0svyC8FnpZ3UMlk5+e5uRBlsse4LGcvE3lSlqDzJPf92arqLewmiHaWkRV612r+7dfFRnoE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NqvBvS9z; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NqvBvS9z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B4E21F00A3D; Mon, 27 Jul 2026 21:00:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785186015; bh=hq0BmK1HWJ+J0wANvmtlXQtwbe5T/XdqsPvwk4NSqQw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=NqvBvS9z2CQhLHErpWAKqWyLdNhM7U3U/mrFgH5V/NBWI2854MatAGSqERW2Rw5tu 2m4VQV83zpyelLY9q33Yrf1Gx8nfRUUB0XBw/9sndpPpCAAjWNsbDyXffcad+wYy66 f/IpgFrh4uvGj6WoPkmKKAnWnUmgy64SQMLmDU6DxleyoKgHMGYM0jcBIKSncdYaOo mQ56cl3sgZzvNpt0zbCXtzohtiUbUCSmGOfnJKWlckaOX9K6zg9i6K2T3wFAjh2vRt ++wEYdsb7WduEjLN6GgoC2SB4yd5kVQ+InKL2/t8vNc0jRMt1FE1dbgwJNIC5Dglle xpDFAuJUeSePw== From: Sasha Levin To: stable@vger.kernel.org Cc: Eric Biggers , Mikulas Patocka , Sasha Levin Subject: [PATCH 6.18.y 3/4] dm-verity-fec: replace {MAX,MIN}_RSN with {MIN,MAX}_ROOTS Date: Mon, 27 Jul 2026 17:00:10 -0400 Message-ID: <20260727210011.1929439-3-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260727210011.1929439-1-sashal@kernel.org> References: <2026072004-monitor-wolf-7764@gregkh> <20260727210011.1929439-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Eric Biggers [ Upstream commit 82fbd6a3e29a329d439690cd7ccc4162c9cd8db6 ] Every time DM_VERITY_FEC_{MAX,MIN}_RSN are used, they are subtracted from DM_VERITY_FEC_RSM to get the bounds on the number of roots. Therefore, replace these with {MIN,MAX}_ROOTS constants which are more directly useful. (Note the inversion, where MAX_RSN maps to MIN_ROOTS and MIN_RSN maps to MAX_ROOTS.) No functional change. Signed-off-by: Eric Biggers Signed-off-by: Mikulas Patocka Stable-dep-of: 31d6e6c0ba8d ("dm-verity: fix buffer overflow in FEC calculation") Signed-off-by: Sasha Levin --- drivers/md/dm-verity-fec.c | 6 +++--- drivers/md/dm-verity-fec.h | 5 ++--- 2 files changed, 5 insertions(+), 6 deletions(-) diff --git a/drivers/md/dm-verity-fec.c b/drivers/md/dm-verity-fec.c index a8fbf97b97517f..cebcc8fd25d700 100644 --- a/drivers/md/dm-verity-fec.c +++ b/drivers/md/dm-verity-fec.c @@ -87,7 +87,7 @@ static int fec_decode_bufs(struct dm_verity *v, struct dm_verity_io *io, int r, corrected = 0, res; struct dm_buffer *buf; unsigned int n, i, j, parity_pos, to_copy; - uint16_t par_buf[DM_VERITY_FEC_RSM - DM_VERITY_FEC_MIN_RSN]; + uint16_t par_buf[DM_VERITY_FEC_MAX_ROOTS]; u8 *par, *block; u64 parity_block; struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); @@ -605,8 +605,8 @@ int verity_fec_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, } else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_ROOTS)) { if (sscanf(arg_value, "%hhu%c", &num_c, &dummy) != 1 || !num_c || - num_c < (DM_VERITY_FEC_RSM - DM_VERITY_FEC_MAX_RSN) || - num_c > (DM_VERITY_FEC_RSM - DM_VERITY_FEC_MIN_RSN)) { + num_c < DM_VERITY_FEC_MIN_ROOTS || + num_c > DM_VERITY_FEC_MAX_ROOTS) { ti->error = "Invalid " DM_VERITY_OPT_FEC_ROOTS; return -EINVAL; } diff --git a/drivers/md/dm-verity-fec.h b/drivers/md/dm-verity-fec.h index 6f11abb3c7d972..178ecdddbbd310 100644 --- a/drivers/md/dm-verity-fec.h +++ b/drivers/md/dm-verity-fec.h @@ -13,9 +13,8 @@ /* Reed-Solomon(M, N) parameters */ #define DM_VERITY_FEC_RSM 255 -#define DM_VERITY_FEC_MAX_RSN 253 -#define DM_VERITY_FEC_MIN_RSN 231 /* ~10% space overhead */ -#define DM_VERITY_FEC_MAX_ROOTS (DM_VERITY_FEC_RSM - DM_VERITY_FEC_MIN_RSN) +#define DM_VERITY_FEC_MIN_ROOTS 2 /* RS(255, 253): ~0.8% space overhead */ +#define DM_VERITY_FEC_MAX_ROOTS 24 /* RS(255, 231): ~10% space overhead */ /* buffers for deinterleaving and decoding */ #define DM_VERITY_FEC_BUF_PREALLOC 1 /* buffers to preallocate */ -- 2.53.0